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Are these spider eggs?


I was pulling weeds in my backyard in Southern California, when I saw a spider over a white area on the underside of one of the leaves. It's staying right near the white spot. Are those spider eggs? Also, what kind of spider is this?


Yes, those are definitely eggs. And I believe that is a female grass spider (Genus: Agelenopsis).

Eggs are typically laid in late summer or fall and spiderlings emerge the following spring… A female that has mated with a male can produce more than one egg sac. For some species, it's common to see two sacs at a time, side by side, attached to a surface (such as the underside of a rock, piece of wood in a wood pile, or in a rolled up leaf, for example). Each different species of Agelenopsis may create a slightly different egg sac, but typically each one contains anywhere from 50 to 200 individual eggs. The mother spider will remain near her eggs, dutifully guarding them, until she dies around the onset of winter.

This seems to fit the picture to a T. I'm not 100% about the species, but I believe it is either A. aperta or A. oregonensis.

Edit:

As user Xan pointed out, this could likely be a lynx spider (Genus: Oxyopes; likely species: Oxyopes salticus - female). This would explain the defined setae (bristles) on the legs. To really decide, you would need to check the following characteristics:

  • Eye pattern: Lynx spider eyes form an octoganal pattern, while grass spider eyes form two, parallel, curved rows.
  • Spinnerets: You would have to search for spinnerets on a lynx spider, while grass spiders have two very prominent hind spinnerets that you can visibly see from above.

I originally thought those were spinnerets in picture 3, but upon closer inspection it looks like one of the hind legs folded underneath.


Spider Eggs Look Like Rock Candy (But Don't Eat Them)

Spider eggs come in brilliant colors and look like candy, as was demonstrated by a striking photo shared to Twitter on June 26.

But lest you be tempted to "taste the rainbow," please hold back, as some spider eggs are known to be toxic, according to a study published in August 2017 in the Journal of Arachnology.

In the image, two vials hold egg clusters from two Australian spider species: One clutch is a brilliant green and comes from a huntsman spider in the Holconia genus, and the other eggs are vibrant yellow and laid by Cyrtophora, or tent-web spiders.

These translucent eggs look a lot like a delicious gummy candy, though when the tweet was circulated around the Live Science newsroom, one of the editors noted that the eggs would be "THE WORST CANDY EVER." [5 Spooky Spider Myths Busted]

The photo is all the more astonishing because spider eggs are so seldom seen, said Glenn King, the scientist who posted the tweet. King is an investigator with the Centre for Pain Research at the University of Queensland (UQ) in Australia his "bugs and drugs" lab analyzes spider venoms as drug candidates for nervous system disorders.

Tiny, delicate spider eggs are usually tucked away in opaque web sacs, and so despite their bright coloration, they are very difficult to spot, King wrote in the tweet.

Scientists with King's lab recently collected the colorful spider eggs on and around the UQ campus: In addition to the green and yellow eggs, there were orange ones produced by spiders in the Argiopegenus and bluish-purple eggs laid by Zosis geniculata, also known as the humped spider, Isaac Tucker, a graduate student at QU, told Live Science in an email.

"We have been able to observe spider eggs from virtually all of the different colors of the rainbow," Tucker said.

But with an estimated 100,000 spider species on the planet, researchers don't know enough about spider eggs to say how many species lay brightly colored eggs, Tucker said.

Just why the eggs are so colorful also remains uncertain, though there may be some clues in another animal group known for colorful eggs &mdash birds.

"In chickens, the different colored eggs are due to differing levels of colored chemicals, which change from species to species, and spiders may follow a similar path," Tucker wrote in the email. "But until further research is conducted we can't be sure."


Most female spiders yield many eggs in order to make sure the species survives. Up to several hundred eggs are put in a sac. Females can create more than one sac but that differs based on the species.

Female spiders’ abdomens may expand due to a high amount of eggs, and their bodies contract after they lay the eggs. Spider eggs are laid during different times. For example, hobo spider females lay eggs in mid-September to October, but brown recluse spiders typically lay eggs between May and July.


Myth: Too many "camel spider" tall tales

Fact: On 4 April 2004 I started getting copies of a mass email, with the picture below attached, saying "From someone stationed in Baghdad . It'll give you a better idea of what our troops are dealing with." Now, the maximum body length of a near-eastern solpugid (non-spider arachnid with no venom whatever) is 5 cm. Those in the picture (around 4 cm long according to a correspondent who knows the sergeant in the photo) appear to be around 40 cm long or 10 times life size, due to false perspective. One suspects the original version was mailed 3 days earlier, on April 1!

"Everything that 'everybody knows' about spiders is wrong!" —Rod Crawford sets the record straight with Spider Myths.


The Infamous Photo. Mass emailed in April 2004 (faked by false perspective solpugids appear 8-10 times life size).

Then, in follow-up messages, the wild claims started to pile up!

  • They call them camel spiders because they eat the stomachs of camels.
  • They attach themselves to the under belly of camels and lay eggs under the skin.
  • They can traverse desert sand at speeds up to 25 miles per hour, making screaming noises as they run.
  • They can jump 4 to 6 feet straight up in the air.
  • They will chase you down like a hungry lion.
  • If they bite you, the flesh and muscle fall off, leaving a hole.
  • They are venomous, and their venom contains a powerful anesthetic that numbs their victims (thus allowing them to gnaw away at living, immobilized animals without being noticed). This builds on a previous myth that spread during the Gulf War.

Solpugids are fast, but not that fast. The maximum speed cited in scientific sources is ten miles per hour, and the only accurately measured speeds I could find were less than 1 mile per hour. Any jumping ability they might have is nothing special. They lay their eggs in the soil, not in camels! They are predatory and do not feed off large animals like camels or humans. When they run toward someone standing in the hot desert sun (or toward their camel or into their tent) they are seeking out shade to hide in. Some species can produce a barely audible stridulation (sounding like a buzz or hiss).

The species in Iraq were studied in Iraq by British scientists during the 39 years (1919-58) the country was under British control. Their anatomy and physiology are well known. They positively have no venom, and no way to inject it even if they did have it! (If they bite and manage to break the skin, the wound is likely to be infected, and such cases may have started some of the stories. Any ill effects could be prevented with disinfectant.) See this article for National Geographic's take on camel spider myths.

I have received (by email) a lot of abuse for doubting these stories – mainly from civilians who probably think it's unpatriotic to doubt the word of a soldier. I have the utmost respect for soldiers but I also know a few, and know that one of their favorite pastimes is sitting around spinning yarns. And why not? They deserve all the diversions they can get. But that doesn't oblige me to believe every tall tale I hear from someone who never, under any circumstances, can give the name of the person it happened to! If the source is an unnamed person ("my nephew," "someone who just returned from Iraq," "shepherds we spoke to," "a Marine," "an airman,"), that's not evidence!

One person offered to have his brother in Iraq send me a 30-cm specimen, but backed down when the brother claimed he couldn't get an export permit. No one has ever explained how they measured speed or jumping height, and of course no one has ever produced a specimen found eating human or camel flesh. But urban legends never die – there's always someone who swears it happened to an unnamed "friend."


Widow Spiders

L. mactans: Eastern North America, eastern Mexico, and the West Indies L. Hesperus: Oklahoma, Kansas, and middle Texas throughout the southwestern states L. geometricus: world wide in the tropical zone.

The potency of the black widow venom is well documented. Since the mouthparts (chelicerae) of the male are very small they are reputed to never bite. All encounters with man and animals can be attributed to the female. The bite of the western black widow has been described to cause a initial pain comparable to the prick of a needle and leaves two red puncture marks caused by the two fangs. This is followed by sharp pain which may lessen or persist for a number of hours. The pain moves from the site of the wound and settles in the abdomen and legs. Other ensuing neurological symptoms include nausea, vomiting, faintness, dizziness, tremors, loss of muscle tone, shock, speech disturbances, and general motor paralysis of various kinds. Anyone that suspects being bitten by a widow spider should seek immediate medical attention. Antivenon (Lyovac) is available for treatment. Death due to widow venom is rare and in untreated patients symptoms rarely persist for more than two days. Recorded deaths in older people were most probably due to complications and/or secondary infections originating at the wound site.

The brown widow spider is the one encountered by most people. And because of the presence of the "hour glass" marking on the ventral side of the spider's abdomen, the brown widow is often mistaken for one of the two black widow spiders. All three species have a black cephalothorax (united head and thorax), dark colored abdomen and long slender legs. Close examination of the brown widow spider shows that the base coloration is more correctly described as a dark brown or mahogany. In addition, the top surface of the abdomen has a distinct pattern of markings. The characteristic that most clearly differentiates the brown widow spider from the two black widows is the surface texture of the egg case. The brown widow egg case is textured and rough in appearance, due to the tufts of silk that are incorporated during the formation of the case. The surface of the black widow egg case is smooth. These egg cases can easily be spoted within the web, most often within the tunnel section where the female spider lives.

The eggs sacs can be constructed by the females in one to three hours and are approximately 1 cm in diameter. Each female can produce 10 to 20 of these sacs during a lifetime, and each sac may contain 200 to 250 eggs. The eggs hatch within the sac in about two weeks.

The spiderlings undergo their first molt three to four days thence. In approximately 10 days they emerge from the sac through one to three holes that are about 1 mm in diameter. The spiderlings remain in the nest area for several weeks (135-240 days) where they undergo six to nine molts before reaching maturity. Female black widows can live 850 to 950 days when food is readily available.

The brown widow spider is the most abundant and is commonly found in urban areas. It may be found indoors however, favorite outdoor hiding places include the crawl space beneath homes and amongst piles of stored lumber, hollow tile blocks, abandoned vehicles, storage sheds, and stored items on shelves. Within the home, the brown widow may be found beneath tables and desks, behind shutters, in the angles of doors and windows, in the folds of clothing, in shoes, and under objects in dark, little-disturbed areas. The black widow spiders are less common and are generally associated with arid areas (western black widow) and higher elevations (southern black widow). Both can be found in crawl spaces, under rocks, in tiny voids, and in utility ducts.

Second instar spiderlings remain near sac but soon after climb to a high point where they spin silk threads and float out on the breeze. This method of "ballooning" provides a general dispersal of these spiders. They are shy and will tend to avoid contact with humans. Females are not aggressive, make no effort to attack, and prefer to retreat and lie perfectly still. When confronted or provoked, however, they will bite and inject a neurotoxic venom.

Their webs are usually about 30 cm in diameter.

Mechanical removal or destruction of these pests is the most satisfactory method of control. These spiders are delicate and can be easily injured or killed with a broom or stick. A vacuum cleaner can also be used to remove adult spiders and their egg cases. If this method is chosen, the vacuum cleaner bag should be removed and secured in a plastic bag for disposal. This will prevent the spiders or spiderlings from crawling out of the cleaner. Storing things neatly and the disposal of rubbish will discourage the formation of webs and nests both inside and outside the home. Periodic inspection of crawl spaces will also help to reduce populations of this pest.

A parasite, Baeus lactrodecti Dozier (Hymenoptera:Scelionidae), was introduced into Hawaii in 1939. This parasite will attack the eggs of L. mactans.

Spider control can be achieved by eliminating or by treating harborage sites with spot applications of an approved insecticide.

Ebeling, W. 1978. Urban Entomology. Division of Agricultural Sciences, University of California, Berkeley.

Funasaki, G. Y., Lai, Po-Yung, et. al. 1988. A review of biological control introductions in Hawaii: 1890 to 1985. Proc. Hawaiian Ent. Soc. 28:105-160.

Gertsch, W. J. 1979. American Spiders. Second edition. Van Nostrand Reinhold Company Inc.

Pinter, L. 1981. Widow spiders in Hawaii. PACDIV NAVFACENGCOM. U.S. Navy. Honolulu. Unpublished report.

Smith, Eric H. and Richard C. Whitman. 1992. NPCA Field Guide to Structural Pests. NPCA.


These spiders can purr

Wolves howl to let others know that they’re around — and maybe even that they are looking for a mate. But not the wolf spider known as Gladicosa gulosa. It makes a kind of a purr. It’s quite a trick for guys of this species. And that’s because it’s not clear that the target of their attentions can actually hear a purr. A female may just feel the effects of that sound as vibrations in her feet. But even that may not happen unless both he and she are standing on the right surface.

Most animal species use sounds to communicate. In fact, Cornell University has created a digital library of more than 200,000 such animal sounds. But for spiders, sound is not a big part of their lives. In fact, they have no ears or other specialized sound-sensing organs.

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So it came as a big surprise to Alexander Sweger when he discovered one species of wolf spider communicates using sound.

Sweger is a behavioral ecologist at the University of Cincinnati in Ohio. He is doing research toward a PhD. In the lab, he works surrounded by wolf spiders. Among these is one species that for almost a century has been known as the purring spider. Biologists suspected this particular type of wolf spider might be using that purring sound to signal its interest in finding a mate. But no one had ever confirmed this, Sweger says.

So he decided to investigate.

Sounds create two types of waves. The first is a short-lived wave. It shifts air molecules around, which is something that can be detected across only a very short distance. This wave is followed by a second, longer-lasting one that causes very local changes in air pressure, explains Sweger.

Most animals, including people, can detect the second wave — usually with their ears. Most spiders can’t. But purring spiders, Sweger and George Uetz now report, can harness leaves and other things in their environment to broadcast and detect vibrations due to sound. The University of Cincinnati scientists described their findings May 21 in Pittsburgh, Pa., at the Acoustical Society of America annual meeting.

How the spider purrs

At mating time, male wolf spiders try to catch a female’s attention by creating “persuasive” vibrations, Sweger says. They strum one structure on their body against another — somewhat as a cricket does — to impress the gals. Getting the message right can be a matter of life and death to the guy who’s doing the wooing. If the female isn’t totally convinced that he’s the “one,” it could be worse than just being rejected, Sweger explains. “She could eat him.” About one out of every five male wolf spiders will be eaten by the female he had been wooing. But the guys who prove suitably persuasive will get to mate — and live to tell the tale.

A spectrogram of the vibrations in a male’s “purr.” The scale shows its frequency on the left axis and time on the bottom axis. Alexander Sweger Purring spiders “are using the same vibratory tactics as every other wolf spider in North America. More or less,” Sweger says. “They’re using the same structures. And they’re making vibrations.”

But the scientists showed that compared to the wooing vibrations made by other wolf spiders, those by Gladicosa gulosa are far stronger.

Sweger discovered something else as well. When a purring spider was on a surface that is good at conducting vibrations, such as leaves, an audible sound was produced.

If a person is within a meter of the courting spiders, they can actually hear the sound. “It’s very soft, but when we’re out in the field, you can hear them,” Sweger says. The sound, he explains, is a bit like a “little strumming chirp” or a “soft rattle or purr.” (You can judge for yourself.)

Wooing with sound

So why bother with an audible sound when a male needs only to convey some persuasive vibrations to a spidey gal? That’s been the real puzzle. And Sweger’s experiments now offer one likely answer: that the sound is just an accident.

The courtship vibrations by purring spiders — at least when leaves or paper are involved — create an audible sound so loud that it can broadcast a guy’s message to a distant gal. But she apparently only “hears” it if she’s also standing on something that can rattle, such as a leaf.

Sweger’s learned this in the lab.

His team let a male purring spider make those wooing “calls.” The scientists then played a sound recording of the guy’s purr through the air. Males in another cage ignored these calls. So did female spiders standing on something solid, such as granite. But if the female was atop a surface that could vibrate, like a piece of paper, then she began moving around. It signaled she had picked up the guy’s message. And it suggests she had to “hear” the audible call as a leaf’s vibrations under her feet before she got the message that a potential mate was out there.

When both spiders are standing on the right kind of surface, a male can broadcast his message over a relatively long distance (a meter or more) for a female to “hear.” At least, Sweger says, based on the new data, “that’s our working hypothesis.”

“This is highly interesting,” says Beth Mortimer. She’s a biologist who studies spiders at the University of Oxford in England, and was not involved in the study. The Cincinnati team’s data suggest “spiders can use materials as a sound detector,” she says. So they, “in a way, are using certain objects [here leaves] as a kind of ear drum, which then transmits vibrations to the spider’s legs.” Although they lack ears, spiders are superb at sensing vibrations, she notes. “This is another great example of the surprising ingenuity of spiders,” she concludes.

Power Words

(for more about Power Words, click here)

acoustics (adj. acoustical) The science of sounds and hearing.

audible Something that can be heard, usually with ears or other sound-sensing structures.

behavioral ecologist A scientist who studies animal behavior in a natural setting.

broadcast To cast — or send out — something over a relatively large distance. A farmer may broadcast seeds by flinging them by hand over a large area. A loudspeaker may send sounds out over a great distance. An electronic transmitter may emit electromagnetic signals over the air to a distant radio, television or other receiving device. And a newscaster can broadcast details of events to listeners across a large area, even the world.

environment The sum of all of the things that exist around some organism or the process and the condition those things create for that organism or process. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature, humidity and placement of components in some electronics system or product.

granite A type of hard igneous rock, which contains coarse-grained inclusions (essentially mini rocks within a rock) of various minerals, chiefly quartz, feldspar and mica.

hypothesis A proposed explanation for a phenomenon. In science, a hypothesis is an idea that must be rigorously tested before it is accepted or rejected.

ingenuity A term for skill, cleverness or inventiveness.

molecule An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

organ (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that interprets nerve signals and a plant’s roots are organs that take in nutrients and moisture.

PhD (also known as a doctorate) A type of advanced degree offered by universities — typically after five or six years of study — for work that creates new knowledge. People qualify to begin this type of graduate study only after having first completed a college degree (a program that typically takes four years of study).

prey Animal species eaten by others.

sensor (in biology) The structure that an organism uses to sense attributes of its environment, such as heat, winds, chemicals, moisture, trauma or an attack by predators.

species A group of similar organisms capable of producing offspring that not only can survive but also reproduce.

vibrate To rhythmically shake or to move continuously and rapidly back and forth.

woo The efforts of a male animal to court a female with the goal of gaining a mate.

Citations

S. Milius. “What’s for dinner? Mom.” Science News for Students. May 7, 2015.

B. Mole. Spidey sense: “Eight-legged pollution monitors.” Science News for Students. December 22, 2014.

S. Ornes. “Quieter vibes for city spiders.” Science News for Students. March 25, 2014.

S. Ornes. “Silky spider footprints.”Science News for Students. June 7, 2011.

E. Sohn. “Hot pepper, hot spider.”Science News for Students. November 9, 2006.

Original Meeting Source: A.L. Sweger and G.W. Uetz. The potential for acoustic communication in the ‘purring’ wolf spider (Abstract 4pAB3). The 169th Acoustical Society of America Meeting, May 21, 2015, Pittsburgh, Pa.

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These 10 fascinating facts about black widow spiders will teach you how to identify them, how they behave, and how to minimize your risk of being bitten.

Widow spiders aren't always black

When most people talk about the black widow spider, they likely think they're referring to a particular spider species. But in the U.S. alone, there are three different kinds of black widows (northern, southern, and western).

And although we tend to refer to all members of the genus Lactrodectus as black widows, widow spiders aren't always black. There are 31 species of Lactrodectus spiders worldwide. In the U.S., these include a brown widow and a red widow.

Only adult female black widows inflict dangerous bites

Female widow spiders are larger than males. It is believed, therefore, that female black widows can penetrate vertebrate skin more effectively than males and inject more venom when they bite.

Nearly all medically significant black widow bites are inflicted by female spiders. Male widow spiders and spiderlings are rarely a cause for concern, and some experts even say they don't bite.

Black widow females rarely eat their mates

Lactrodectus spiders are widely thought to practice sexual cannibalism, where the smaller male is sacrificed after mating. In fact, this belief is so widespread the term "black widow" has become synonymous for femme fatale, a kind of seductress who lures men with the intention of bringing harm to them.

But studies show that such behavior is actually quite rare in widow spiders in the wild, and even uncommon among captive spiders. Sexual cannibalism is actually practiced by quite a few insects and spiders and is not unique to the often maligned black widow.

Most (but not all) widow spiders can be identified by a red hourglass marking

Nearly all black widow females bear a distinct hourglass-shaped marking on the underside of the abdomen. In most species, the hourglass is bright red or orange, in sharp contrast to its shiny black abdomen.

The hourglass may be incomplete, with a break in the middle, in certain species like the northern black widow (Lactrodectus variolus). However, the red widow, Lactrodectus bishopi, does not have an hourglass marking, so be mindful that not all widow spiders are identified by this feature.

Black widow spiderlings look nothing like the black and red spiders we recognize as black widows

Widow spider nymphs are mostly white when they hatch from the egg sac. As they undergo successive molts, the spiderlings gradually darken in color, from tan to gray, usually with white or beige markings.

Female spiderlings take longer to reach maturity than their brothers but eventually turn dark black and red. So that drab, pale little spider you found just might be a widow spider, albeit an immature one.

Black widows make cobwebs

Black widow spiders belong to the spider family Theridiidae, commonly called the cobweb spiders. These spiders, black widows included, construct sticky, irregular silk webs to ensnare their prey.

Members of this spider family are also referred to as comb-foot spiders because they have a row of bristles on their back legs to help them wrap silk around their prey. But no need to worry. Although they are closely related to the house spiders building cobwebs in the corners of your home, black widows rarely come indoors.

Female black widows have poor eyesight

Black widows rely on their silk webs to "see" what's going on around them because they can't see very well. The black widow female usually hides in a hole or crevice and builds her web as an extension of her hiding spot. From the safety of her retreat, she can feel the vibrations of her web when either prey or predator comes in contact with the silk threads.

Male widow spiders looking for mates use this to their advantage. The male black widow will cut and rearrange the female's web, making it difficult for her to sense what's happening, before carefully approaching her to mate.

Black widow venom is 15 times as toxic as that of the prairie rattlesnake

Widow spiders do pack a powerful punch of neurotoxins in their venom. By volume, Lactrodectus venom is an extremely toxic mix of poisons capable of causing muscle cramps, severe pain, hypertension, weakness and sweating in bite victims.

But black widow spiders are significantly smaller than rattlesnakes, and they're built for subduing other small invertebrates, not large mammals like people. When a black widow spider bites a person, the volume of neurotoxins injected in the victim is small.

Black widow spider bites are rarely fatal

Although black widow bites can be painful and require medical treatment, they are very rarely fatal. In fact, the majority of black widow bites cause only mild symptoms, and many bite victims don't even realize they were bitten.

In a review of over 23,000 documented Lactrodectus envenomation cases that occurred in the U.S. from 2000 to 2008, the study authors noted that not a single death occurred as a result of a black widow bite. Only 1.4% of bite victims suffered "major effects" of black widow venom.

Before the invention of indoor plumbing, most black widow bites occurred in outhouses

Black widows don't often invade homes, but they do like to inhabit human-built structures like sheds, barns, and outhouses. And unfortunately for those who lived before the water closet was commonplace, black widows like to retreat under the seats of outdoor privies, perhaps because the smell attracts so many delicious flies for them to catch.

Men who use pit toilets should be aware of this disturbing little factoid – most black widow bites are inflicted on penises, thanks to their tendency to dangle threateningly into the black widow's territory beneath the seat. A 1944 case study published in the Annals of Surgery noted that, of 24 black widow bite cases reviewed, eleven bites were on the penis, one was on the scrotum, and four were on the buttocks. A full 16 of the 24 victims were bitten while sitting on the toilet.


Are these spider eggs? - Biology

The predatory mite Neoseiulus californicus (McGregor) has characteristics of both type II specialist predatory mites and type III generalist predatory mites. Neoseiulus californicus prefers Tetranychid mites as food, but will also consume other mite species, small insects, such as thrips, and even pollen when the primary prey is unavailable.

Neoseiulus californicus is often used to control the twospotted spider mite, Tetranychus urticae Koch, and other phytophagous mites on various crops in temperate and subtropical regions around the world.

Figure 1. Adult Neoseiulus californicus (McGregor) feeding on a twospotted spider mite, Tetranychus urticae Koch. Photograph by Lyle Buss, University of Florida.

Synonymy (Back to Top)

Neoseiulus californicus has a very complex taxonomic history. It was first described by McGregor in 1954 from lemon in California as Typhlodromus californicus. After 1954, it was moved to the genus Amblyseius and later to the genus Neoseiulus or Cydnodromus, and now Neoseiulus chilenensis (Dosse) is considered a synonym of Neoseiulus californicus.

Distribution (Back to Top)

Natural populations of Neoseiulus californicus, are found in Argentina, California, Chile, Florida, Japan, South Africa, Texas, parts of southern Europe, and all along the border of the Mediterranean Sea. Neoseiulus californicus has been found on many crops including avocado, citrus and other fruit trees. They are also found on cassava, corn, grapes, strawberries, and several vegetable crops and ornamental plants. They prefer warm 10-33°C (50-91°F) temperatures, but they can tolerate much colder temperatures for short periods of time. For example, they can survive the winters in north Florida where temperatures can fall below freezing at night. They can tolerate a wide range of humidity (40-80% relative humidity), but prefer humidity at the upper end of this range.

Description (Back to Top)

Neoseiulus californicus eggs are football shaped, approximately 0.04 mm (0.00016 inch) in length, and are pale whitish in color. Larvae have only six legs and are translucent in color. Both nymphal stages, the protonymph and the deutonymph, resemble the adults except that they are smaller and cannot reproduce. Adult females are approximately 0.1 mm (0.00039 inch) in length and oval in shape. Males are slightly smaller than females. Both males and females are translucent and can be pale orange, peach, or pink in color.

Figure 2. Two eggs of Neoseiulus californicus (McGregor) attached to leaf hairs on a strawberry leaf. Photograph by Elena M. Rhodes, University of Florida.

Figure 3. Dorsal view of a Neoseiulus californicus (McGregor) larva indicated by pointer. An adult Neoseiulus californicus and a cluster of spider mite eggs are shown for size comparison. Photograph by Jack Kelly Clark, University of California.

Figure 4. Dorsal view of adult female Neoseiulus californicus (McGregor) on a strawberry leaf. Photograph by Elena M. Rhodes, University of Florida.

Life Cycle (Back to Top)

Neoseiulus californicus females can lay up to four eggs a day. However, two eggs per day is the average. Eggs take from 1.5 to 4.0 days to hatch depending on the temperature. Eggs hatch into six-legged larvae, which can progress to the protonymphal stage without feeding. The larval stage can last from 0.5 to 1.0 day. Neoseiulus californicus then passes through two nymphal stages: protonymph and deutonymph. Both stages (protonymph and deutonymph) are active feeders. Each nymphal stage can last from 1.0 to 3.0 days. Total developmental time can be as short as 4.0 days or as long as 12.0 days depending on the temperature. Neoseiulus californicus develops more quickly at higher temperatures. Adults live for approximately 20 days.

Neoseiulus californicus develops faster when consuming the twospotted spider mite, Tetranychus urticae Koch, than when consuming other prey sources. However, it will also successfully develop and reproduce when consuming other mite species including: Aculus schlechtendali (Nalepa), Oligonychus pratensis (Banks), Oligonychus perseae Tuttle, Oligonychus ilicis (McGregor), Panonychus ulmi (Koch), Phytonemus pallidus (Banks), Polyphagotarsonemus (Stenotarsonemus) latus Banks (the broad mite), and Phytonemus pallidus L. (the cyclamen mite). Many of these mites are crop pests. It can also survive and reproduce by consuming thrips and other small insects, but reproduction is very low. Neoseiulus californicus can even survive for a short period of time by consuming only pollen.

Figure 5. A strawberry leaf infested with twospotted spider mite, Tetranychus urticae Koch, adults and their eggs. Photograph by Lyle Buss, University of Florida.

Economic Importance (Back to Top)

Neoseiulus californicus is used commercially around the world to control the twospotted spider mite and several other economically important mites on avocado, citrus, dwarf hops, grapes, raspberries, roses and other ornamentals, strawberries, and several vegetable crops. It has been shown to effectively control the twospotted spider mite and Phytonemus pallidus on strawberries in glasshouses in the UK and in greenhouses in Argentina. In the U.S., Neoseiulus californicus has been used successfully to control twospotted spider mites on field grown strawberries in southern California and Florida. Neoseiulus californicus has also been used to control the twospotted spider mite on dwarf hops and to control Oligonychus perseae on avocado, to mention a few examples.

The recommended release rate depends on pest species, pest density, and crop. In strawberry, a release rate of one female Neoseiulus californicus per 10 twospotted spider mites is recommended once mites are present. A predator in first technique, where Neoseiulus californicus is released at a low rate before twospotted spider mites infestations appear, has become popular in California strawberries. If twospotted spider mire populations are already high, it may be necessary to spray a miticide before releasing Neoseiulus californicus. The predatory mite can tolerate applications of some miticides.

Figure 6. Commercial presentation of Neoseiulus californicus (McGregor) to be released on the field (courtesy of Koppert Biological Supply Co.). Photograph by Elena Rhodes, University of Florida.

Selected References (Back to Top)

  • Barber A, Campbell CAM, Crane H, Lilley R, Tregidga E. 2003. Biocontrol of two-spotted spider mite Tetranychus urticae on dwarf hops by the phytoseiid mites Phytoseiulus persimilis and Neoseiulus californicus. Biocontrol Science and Technology 13: 275-284.
  • Castagnoli M, Simoni S. 2003. Neoseiulus californicus (McGregor) (Acari: Phytoseiidae): survey of biological and behavioral traits of a versatile predator. Redia 86: 153-164.
  • Castagnoli M, Liguori M. 1991. Laboratory observations on duration of copulation and egg production of three Phytoseiid species fed on pollen. In: The Acari. Chapman and Hall, New York, NY. 231-239.
  • Croft BA, Monetti LN, Pratt PD. 1998. Comparative life histories and predation types: are Neoseiulus californicus and N. fallacies (Acari: Phytoseiidae) similar type II selective predators of spider mites. Environmental Entomology 27: 531-538.
  • Easterbrook MA, Fitzgerald JD, Solomon MG. 2001. Biological control of strawberry tarsonemid mite Phytonemus pallidus and two-spotted spider mite Tetranychus urticae on strawberry in the UK using species of Neoseiulus (Amblyseius) (Acari: Phytoseiidae). Experimental & Applied Acarology 25: 25-36.
  • Fraulo AB, McSorley R, Liburd OE. 2008. Effects of the biological control agent Neoseiulus californicus (Acari: Phytoseiidae) on arthropod community structures in north Florida strawberry fields. Florida Entomologist 91: 336-345.
  • Gerson U, Smiley RL, Ochoa R. 2003. Mites (Acari) For Pest Control. Blackwell Publishing. Ames, IA. 556 pp.
  • Greco NM, Liljesthrom GG, Sanchez NE. 1999. Spatial distribution and coincidence of Neoseiulus californicus and Tetranychus urticae (Acari: Phytoseiidae, Tetranychidae) on strawberry. Experimental and Applied Acarology 23: 567-580.
  • Hoddle MS, Aponte O, Kerguelen V, Heraty J. 1999. Biological control of Oligonychus perseae (Acari: Tetranychidae) on avocado: evaluating release timing, recovery, and efficacy of six commercially available phytoseiids. International Journal of Acarology 25: 211-219.
  • Johnson WT, Lyon HH. 1991. Insects That Feed on Trees and Shrubs. 2nd edition. Comstock Publishing Associates. 560 pp.
  • Krantz GW. 1978. A Manual of Acarology. Corvallis. Oregon State University, OR. 509 pp.
  • Liburd OE, Seferina GG, Dinkins DA. 2003. Suppression of twospotted spider mites. In: UF/IFAS Berry/Vegetable Times. November 2003.
  • Ma W-L, Laing JE. Biology, potential for increase and prey consumption of Amblyseius chilenesis (Dosse) (Acarina: Phytoseiidae). Entomophaga 18: 47-60.
  • McMurtry JA, Croft BA. 1997. Life-styles of Phytoseiid mites and their roles in biological control. Annual Review of Entomology 42: 291-321.
  • Oatman, ER, McMurtry JA, Gilstrap FE, Voth V. 1977. Effect of releases of Amblyseius californicus on the twospotted spider mite on strawberry in Southern California. Journal of Economic Entomology 70: 638-640.
  • Rondon SI, Price JF, Liburd OE, Francis R, Cantliff DJ. (2004). Neoseiulus californicus(McGregor). A predatory mite species for controlling twospotted spider mites in strawberries. EDIS. (31 October 2005).

Authors: Elena M. Rhodes and Oscar E. Liburd, University of Florida
Photographs: Elena Rhodes and Lyle J. Buss, University of Florida and Jack Kelly Clark, University of California
Web Design: Don Wasik, Jane Medley
Publication Number: EENY-359
Publication Date: November 2005. Latest revision: August 2015.


Are these spider mite eggs? Microscope pics..

I thought I was deadling with thrips but do these look like spider mites. One is pic is from the front the other the back of the leaf. If these are spider mite eggs then they are on almost every leaf but where there are the most eggs there is the most damage.

I have not seen any webs or any spider mites. These pics are from one of the worst leaves

Here is pic from google of spider mite eggs

Attachments

Cdrippper2

Active Member

Playboy420

Member

Thanks for the reply, It looksl just like the pic!! THis is a fan leaf. I am in 100% canna coco 25 days into veg with huge bushes. I should be giving them 1000ppm but I am only doing 700 becuase I thought it was burn..

Idk what to do anymore ha

ANy one else care to comment? It looks so much like the picture tho.

Crazeehaze

Well-Known Member

how far along are the plants? could it be trichomes forming at all? very hard to tell on the pics tbh..
but so many eggs and you cannot spot any mites sounds odd in that case..

leaf looks like some nute burn alittle but the leaf finger to the far right almost looks like there is a trail from a leaf miner.. but this is indoor grow right? they usually only come outdoors.. man i dont know.

Aficionado

Active Member

Rarely will you find spider mite eggs w/o spider mites present. Webbing typically forms when the population of mites is large enough where they colonize and spin a web farm. You will also see small black fecal matter near where they live, and the tell tell signs of small yellow dots where they puncture the leaf to feed (think speckled candy easter eggs).

Your pictures look like underdeveloped trichomes. If you are not seeing actual mites, my guess is that this is what it is.

Playboy420

Member

Thank you very much everyone, I am indoors about 1 month into veg. I have been using neem oil bi-weekly since I started to see some fungus gnats. That was 3 weeks ago Ive since killed the gnats.

I have had some nute damage so..I just cant explain the brown spots on my leaves. It looks like ph but then I think its thrips so I dont know!

I will get some more pics up later after work, thank you every one again.

Jumpstart

Member

Thank you very much everyone, I am indoors about 1 month into veg. I have been using neem oil bi-weekly since I started to see some fungus gnats. That was 3 weeks ago Ive since killed the gnats.

I have had some nute damage so..I just cant explain the brown spots on my leaves. It looks like ph but then I think its thrips so I dont know!

I will get some more pics up later after work, thank you every one again.

Thanks for posting the micro pics. Spider mite eggs and tricomes on vegging leaves undersides look a lot alike !
I too was looking at back side of leaves and saw these "eggs" . I do not have mites and the grow room plant with the most of these 'eggs' is an older (2 month) plant. Some are clear and others are white. The younger plants also have some 'eggs' but not as much. Wonder why this discussion hasn't cropped up before.


Habitat

It has been estimated that more than 40,000 species of spiders inhabit the earth. They are found on every continent except for Antarctica and have become established in nearly every habitat, excepting only the air. The vast majority of spiders are terrestrial, with only a few specialized species able to live in freshwater.

Spiders decide where to live based largely on the availability of prey and potential for reproduction. They will usually construct a web to scope out a potential nesting location as they try to determine whether there will be enough food and a place for them to lay their eggs. Some spiders tend to judge an area based on the presence (or lack) of other spiders and may even force their competitors from their webs, claiming them for themselves, if they deem a location sufficient for nesting.

Almost all spiders produce silk. Silk-producing spinnerets are usually located under the tip of a spider's abdomen, which enables them to spin a long strand of silk behind them. Silk production is no simple endeavor for spiders as it requires great time and energy. Because of this, some species have been recorded consuming their own silk when they are finished with it to store for later use.

There are many different types of silk and each type serves a different function for the spider.

Types of Silk and Their Functions

  • Attachment: clinging to surfaces
  • Cocoon: forming a protective case for eggs
  • Dragline: web construction
  • Glue-like: capturing prey
  • Minor: web construction
  • Viscid: capturing prey
  • Wrapping: wrapping prey in silk to allow for consumption

Spider silk is highly regarded as a marvel of engineering by scientists for its structural properties. It is fine yet strong, resistant to many solvents, and even possesses thermal conductivity properties. Researchers have been studying spider silk for years in the hopes of understanding it well enough to manufacture a synthetic version for human use.


Fact or Fiction?: People Swallow 8 Spiders a Year While They Sleep

Should we worry about arachnids crawling into our mouths while we&rsquore in dreamland?

Rod Crawford has heard plenty of firsthand accounts of spider-swilling slumberers. &ldquoOnce or twice a year, someone tells me they once recovered a spider leg in their mouth,&rdquo says Crawford, the arachnid curator at the Burke Museum of Natural History and Culture in Seattle.

Luckily for all of us, the &ldquofact&rdquo that people swallow eight spiders in their sleep yearly isn&rsquot true. Not even close. The myth flies in the face of both spider and human biology, which makes it highly unlikely that a spider would ever end up in your mouth.

Three or four spider species live in most North American homes, and they all tend to be found either tending their webs or hunting in nonhuman-infested areas. During their forays, they usually don&rsquot intentionally crawl into a bed because it offers no prey (unless it has bed bugs, in which case that person has bigger problems). Spiders also have no interest in humans. &ldquoSpiders regard us much like they&rsquod regard a big rock,&rdquo says Bill Shear, a biology professor at Hampden&ndashSydney College in Virginia and former president of the American Arachnological Society. &ldquoWe&rsquore so large that we&rsquore really just part of the landscape,&rdquo

More than anything, spiders probably find sleeping humans terrifying. A slumbering person breathes, has a beating heart and perhaps snores&mdashall of which create vibrations that warn spiders of danger. &ldquoVibrations are a big slice of spiders&rsquo sensory universe,&rdquo Crawford explains, &ldquoA sleeping person is not something a spider would willingly approach.&rdquo

From the standpoint of human biology, the oral spider myth also seems ridiculous. If someone is sleeping with her mouth open, she&rsquos probably snoring&mdashand thus scaring off any eight-legged transgressors. Plus, many people would likely be awakened by the sensation of a spider crawling over their faces and into their mouths. Shear can attest: once, while camping, he awoke to find a daddy longlegs crawling on his face.

Spider experts concede that a sleeping person could plausibly swallow a spider, but &ldquoit would be a strictly random event.&rdquo People who claim they&rsquove swallowed spiders never seem to have any concrete evidence. &ldquoPeople tell me this happened to them, but they threw it (the evidence) away&mdashflushed it down the toilet, usually,&rdquo Crawford says. There&rsquos also a sore lack of eyewitnesses for such a frequent event as eight spiders a year. So even if you heard or read this spider statistic from a trustworthy source (such as a Snapple cap), you can rest assured that it doesn&rsquot have a leg, or eight legs, to stand on.