How Many Spiders?

I’ve been sick for a few days now, so I haven’t put any real time into the “what are these fossils” article I promised last time. Instead, let’s look at something comparatively simple. I picked up my son from Kindergarten yesterday. Normally, since I was home and it’s only about a quarter mile, we’d have walked. But, like I said, I’ve been sick. So he’s in the back seat excitedly telling me about his Valentine’s Day party. “Dad?” he asks as we pull into our garage.

“Yes, son?” I respond.

“How many spiders can you carry?”

No, I have no idea where that came from. But I’ve gotten used to that by now. “Well,” I say, “that depends on how big they are, and how cooperative they are.”

So, how many could you carry?

“I could carry a hundred spiders!” he declares.

“Maybe,” I tell him. “If you could put them in a box. Or if they were tiny and well-trained.”

So, how many could you carry? Like I said, it depends on the spider. The good people at Guinness World Records say the Patu marplesi is the smallest spider, while Wikipedia contradicts them and states that a related species – the Patu digua is the smallest. Either way, it’s a tiny spider – the body size is only 0.37 mm – and the author of Catalog of Organisms states that “If one of these spiders crawled into your ear while you were sleeping, it could probably slip into your Eustachian tubes and tap on the back of your eyeballs.” So try not to think too hard about that.

patu-digua

“Peek-a-boo!”

I couldn’t find anything at all about how much (little?) this critter weighs. So, I’m going to run the risk of estimating. Here’s what I did, so that you can play the home game. I found an article titled “Estimating Live Spider Weight Using Preserved Specimens” from The Journal of Arachnology in 1996. It provides a formula for calculating weight from length for spiders: ln weight = 1.844 + 2.711(ln length), and seems to indicate that the weight is read in milligrams (mg) and the length in millimeters (mm). So, that would give us ln weight = -1.844 + 2.711(ln 0.37). That works out to… let’s see…

  1. ln weight = -1.844 + 2.711(ln 0.37)
  2. ln weight = -1.844 + -2.695
  3. ln weight = -4.539
  4. e^ln weight = e^-4.539
  5. weight = 0.010684 mg

So, one 0.37 mm spider appears to weigh 0.01 mg. How many of these could we move? Let’s find out?

Bare Hands

My palm is, roughly speaking, a 9 cm by 9 cm (90 mm by 90 mm) square. That gives me 8,100 mm of surface area, so I could stack a single layer of 8,100/0.37 = 21,891 well behaved Patu digua on one hand. Using both hands, I could carry 43,782 of them. The two-hand load would come out to 0.43782 grams, or 0.0015 ounces of spider.

Let’s try and do more. If I cup my hands, I get a sort of rounded cone that’s 7 cm (70 mm) in diameter by 7 cm (70 mm) deep. That gives me a volume of 359,189 cubic mm. Now, let’s assume that the Patu digua takes up the same volume as a sphere 0.37 mm in diameter. That’s 0.212175 cubic mm. So, in my cupped hands, I could carry 359,189/0.212175 = 1,692,890 Patu digua. Those guys would weigh in at 18.0868 grams (0.63799 ounces).

We’re not savages, you know

Yes, I know. So let’s fill a box. A standard U-Haul shipping box is 41.5″ (1054.1 mm) x 38.5″ (977.9 mm) x 18.75″ (476.25), for a volume of 429,072,327.3375 cubic mm. That means I could carry 429,072,327.3375/0.212175 = 202,256,756 of the little spiders – 21.606 kg (47.6 pounds) of Patu digua. My son weighs more than that, so I know for a fact that I could easily carry that box of spiders from my house to my car, and then from the car to the Post Office, and then from the Post Office back to my car because the USPS would most likely refuse to accept that package.

Cool. What about big spiders?

National Geographic informs me that the South African Goliath Birdeater Tarantula is the biggest spider in the world as measured by body size. Nothing I could find gave me an explicit size, but terms like “puppy sized” and “the size of a dinner plate” were bandied about with distressing familiarity. National Geographic also states that:

Many of the locals in northeastern South America regard T. blondi as a tasty snack. They first singe off the urticating hairs, then wrap the spider in banana leaves to roast it. Tarantula expert Rick West, who once sat down for a meal of these spiders with the local Piaroa people of Amazonas in Venezuela, says T. blondi can be surprisingly tasty and moist. (Also see “UN Urges Eating Insects; 8 Popular Bugs to Try.”)

“The white muscle ‘meat’ tastes like smoky prawns, while the gooey abdominal contents is hard-boiled in a rolled leaf and tastes gritty and bitter,” West says. “The three-quarter-inch [two-centimeter] fangs are used after the meal as toothpicks to remove T. blondi exocuticle from between one’s teeth.”

goliath

“I’m tasty!”

On the other hand, if you’re measuring by legspan the prize goes to the giant huntsman spider, with a leg span over one foot (30.48 cm) across. No word on how they taste, though.

huntsman

“Come on and have a go, if you think you’re hard enough!”

Without specifics, I can’t tell you how many I could handle. One per hand, maybe, and maybe four in a shipping crate. But, on the other hand?  Oh my god no.

Advertisements

Why Does A Stinkbug Stink?

“Look, dad!” my son shouts, voice excited as he points. “A stinkbug!”

We’re walking up the front stairs to our condo. I glance in the direction he’s pointing, and see nothing.  “Cool,” I tell him.

“Why do stinkbugs stink?” he asks.

I unlock the front door. “I don’t know,” I answer. “I think maybe they spray stinky chemicals.”

What is a stinkbug?

Getting information on stinkbugs in general proved to be a little difficult, as Google just keeps giving me hits for the Brown Marmorated Stink Bug (Halyomorpha halys), an insect native to China and Japan that is an invasive species in North America.  Wikipedia, when you do a search for ‘stink bugs’, takes you to a page about family Pentatomidae, a family of insects belonging to order Hemiptera.  Shield bugs and stink bugs belong to Hemiptera, with stink bugs comprising Pentatomidae.

I couldn’t find a list of the species native to North America.  Heck, I couldn’t even find a list of the species of Pentatomidae, end of statement.  But, here’s a brown stink bug that is native to this continent:

native_brown_1242026

That particular bug is Euschistus servus, and it is a common pest throughout southern Canada and the northern United States.  This particular bug is about half an inch long (10 to 15 mm), and lays a bright yellow egg mass (around 60 eggs) that turns pinkish as they get ready to hatch (between four and five weeks after being laid).  Larval stink bugs require about 29 days to reach maturity.  Adults are able to fly, and are primarily omnivores.

Brown stink bugs often feed on the vegetative parts, flowers, stems and foliage of the plant, as well as the seed, nut or fruit, and this makes them important pests of many crops.

Brown stink bugs are found on a variety of hosts, such as shrubs, vines, many broadleaf weeds, especially legumes, as well as cultivated crops such as corn, soybean, sorghum, okra, millet, snap beans, peas and cotton.

Do stinkbugs stink?

Yes, they do.  Here’s what Orkin has to say on the subject:

Their name comes from their smelly defense mechanism. Stink bugs have the ability to emit a strong deterring odor, from their body glands, whenever they feel threatened or injured — much like how a skunk defends itself. The smell varies depending on the species and the person’s olfactory senses, but it has often been compared to strong herbs and spices like cilantro and coriander.

Interesting enough, the composition of the odor is comprised of chemicals commonly used as food additives and is present in cilantro. This smell can linger for hours so, if possible, try to avoid stink bugs or carefully sweep or vacuum them up if they have entered your house, unless you want a face full of intense-smelling herbs and spices.

A more detailed description of the specific chemicals used by one particular species of stink bug may be found in Chemical Defense in the Stink Bug Cosmopepla bimaculata, an article published in the Journal of Chemical Ecology back in 1999 and freely available on the internet.  From the abstract,

Adult Cosmopepla bimaculata discharge a volatile secretion from paired ventral metathoracic glands (MIG) when disturbed. Collected volatiles were similar in both sexes and consisted of n-tridecane (67%), (E)-2-decenal (12%), (E)-2-decenyl acetate (12%), (E)-2-hexenal (3%), hexyl acetate (2%), n-dodecane (2%), a tridecene isomer (l%), and n-undecane, n-tetradecane, and n-pentadecane (all <1%). In addition. undisturbed males produced a novel insect compound. (E)-8-heneicosene. whose function is unknown.

No, I don’t know what any of those are.  But every resource I found agrees on a few things about stink bug spray:

  1. It smells vaguely of spices and cucumber
  2. Despite that, it does not smell good.
  3. No, really, it stinks like old garbage.

So, to answer the original question, why do stink bugs stink?  Because they don’t want to get eaten.  Again, as the abstract of Chemical Defense in the Stink Bug Cosmopepla bimaculata put it, “In feeding trials, killdeer (Charadrius vociferus), starlings (Sturnus vulgaris), robins (Turdus migratorius), and anole lizards (Anolis ccarolinensis) rejected or demonstrated aversion to feeding on the bugs. Furthermore. bugs that lacked the secretion were more susceptible to predation than bugs with secretion, suggesting that the secretion functions in defense against predators.”

 

Why are there bugs in his hair?

My son attends a preschool, and we just found out that head lice are going around. This was a source of some concern for my son, because what he knows about it starts with “bugs in hair, bugs in hair!” and ends with “they make you itch!” So, naturally, he’s had some questions about them. Lots of questions. And, to tell the truth, so do I. Because I remember distinctly that, when I grew up, there was a social stigma associated with having lice. Not just because you had bugs in your hair, but because it meant you were perceived as filthy and dirty.

That’s hardly a fair assumption, of course. My son’s daycare and preschool is a wonderful place and they take hygene seriously. But it’s hard to shake beliefs that get ingrained during childhood. Also, it turns out that I know next to nothing about head lice. Beyond “bugs in hair, bugs in hair!”

What are head lice?

head-lice

That picture up there? That’s a head louse – Pediculus humanus capitis – an obligate ectoparasite of humans, which is a fancy way of saying it’s a parasite that lives on human skin and needs to exploit a host as part of its life cycle. Pediculus humanus capitis feeds by biting the skin and injecting an anti-coagulant in order to suck blood (producing a dark red poop when digested), and generally colonizes the scalp (particularly the nape of the neck and the back of the ears).

lice_lifecycle

According to the CDC,

The life cycle of the head louse has three stages: egg, nymph, and adult.

Eggs: Nits are head lice eggs. They are hard to see and are often confused for dandruff or hair spray droplets. Nits are laid by the adult female and are cemented at the base of the hair shaft nearest the scalp. They are 0.8 mm by 0.3 mm, oval and usually yellow to white. Nits take about 1 week to hatch (range 6 to 9 days). Viable eggs are usually located within 6 mm of the scalp.

Nymphs: The egg hatches to release a nymph. The nit shell then becomes a more visible dull yellow and remains attached to the hair shaft. The nymph looks like an adult head louse, but is about the size of a pinhead. Nymphs mature after three molts and become adults about 7 days after hatching.

Adults: The adult louse is about the size of a sesame seed, has 6 legs (each with claws), and is tan to grayish-white The number 5. In persons with dark hair, the adult louse will appear darker. Females are usually larger than males and can lay up to 8 nits per day. Adult lice can live up to 30 days on a person’s head. To live, adult lice need to feed on blood several times daily. Without blood meals, the louse will die within 1 to 2 days off the host.[/quote]

Wikipedia expands on the definition of “nit” a little, stating that “the term nit refers to an egg without embryo or a dead egg”.

Pediculus humanus capitis requires anywhere from 8 to 24 days to mature from a newly-hatched nymph to a sexually mature adult, depending on temperature and access to blood. Once mature, a female can lay 3-4 eggs per day for pretty much rest of her life (which can be up to 30 days from hatching). This is under optimal conditions of course.

Ick. So, how does it spread?

Turning to the Centers for Disease Control once more,

Head lice are mainly spread by direct contact with the hair of an infested person. The most common way to get head lice is by head-to-head contact with a person who already has head lice. Such contact can be common among children during play at:

  •  school,
  • home, and
  • elsewhere (e.g., sports activities, playgrounds, camp, and slumber parties).

Uncommonly, transmission may occur by:

  • wearing clothing, such as hats, scarves, coats, sports uniforms, or hair ribbons worn by an infested person;
  • using infested combs, brushes or towels; or
  • lying on a bed, couch, pillow, carpet, or stuffed animal that has recently been in contact with an infested person.

Reliable data on how many people get head lice each year in the United States are not available; however, an estimated 6 million to 12 million infestations occur each year in the United States among children 3 to 11 years of age. Some studies suggest that girls get head lice more often than boys, probably due to more frequent head-to-head contact.

Interestingly, they note that (in the United States, at least) African-Americans are less likely to have an infestation than other races. They don’t quite know why, but speculate that the most common head louse in the United States is not well adapted to grasping the shape and width of some types of hair. Sadly, if you’re African-American and reading this, you can’t simply assume that you’re immune to head lice infestations. After all, “less likely” is not the same thing as “can’t get it”.

The CDC also states the following: “Head lice move by crawling; they cannot hop or fly. Head lice are spread by direct contact with the hair of an infested person. Anyone who comes in head-to-head contact with someone who already has head lice is at greatest risk. Spread by contact with clothing (such as hats, scarves, coats) or other personal items (such as combs, brushes, or towels) used by an infested person is uncommon. Personal hygiene or cleanliness in the home or school has nothing to do with getting head lice.” To be safe, you probably still don’t want to share hats or combs or the like. But you should really avoid headbutting.

How do I know if I (or someone else) has lice?

Unsurprisingly, the CDC has a lot to say about this. Symptoms include:

  • Tickling feeling of something moving in the hair.
  • Itching, caused by an allergic reaction to the bites of the head louse.
  • Irritability and difficulty sleeping; head lice are most active in the dark.
  • Sores on the head caused by scratching. These sores can sometimes become infected with bacteria found on the person’s skin.

However, they also note that “Misdiagnosis of head lice infestation is common. The diagnosis of head lice infestation is best made by finding a live nymph or adult louse on the scalp or hair of a person…. If crawling lice are not seen, finding nits attached firmly within ¼ inch of the base of hair shafts suggests, but does not confirm, the person is infested. Nits frequently are seen on hair behind the ears and near the back of the neck. Nits that are attached more than ¼ inch from the base of the hair shaft are almost always non-viable (hatched or dead). Head lice and nits can be visible with the naked eye, although use of a magnifying lens may be necessary to find crawling lice or to identify a developing nymph inside a viable nit. Nits are often confused with other particles found in hair such as dandruff, hair spray droplets, and dirt particles.”

Yeah, that’s distinctly a bug. Now what?

Are you shocked to learn that the CDC has information on this as well? No? Me neither. The first thing that they recommend is, after confirming that someone in the household has an active infestation, you should check everyone else in the same household. It’s most likely to spread within a family, after all, as family members have the greatest odds of coming into head-to-head contact.

Pharmacologically speaking, you can use an over-the-counter or prescription medicine to kill the lice and nits. Be sure to follow the directions and, if the infested individual has long hair, consider more than one treatment. The CDC also recommends not re-washing hair for one to two days after treatment, to allow the residue of the medicine to continue to work. After treatment, comb the infested individual’s hair thoroughly to remove lice and nits and then check them around 8-12 hours after treatment. A few live but sluggish lice found during that time generally doesn’t mean that the treatment failed (some are more resistant than others), and you probably won’t need to retreat. If the lice are still active,, however, you may wish to use a different medicine and/or consult with a health care professional. Also, even after the lice appear gone, you should comb the hair with a nit comb every two to three days for the next two to three weeks to ensure the infestation is gone. Also, if the specific medicine you are using has different instructions, follow them.

Any clothing, bed linens, plush animals, etc that the infested individual came into contact with should be washed on hot (130 degrees F or higher) and then dried on the high heat cycle. Items that are not machine washable can be dry-cleaned instead, or sealed in plastic bags for two weeks. Vacuuming furniture and carpets can remove any lice that have fallen from the infested person, but they generally do not survive long off a human (since they are human-exclusive parasites that need human blood to live) so you don’t have to go to extreme measures to sterilize your home.

Kill it. Kill it with fire!

Generally speaking, you don’t actually kill head lice with fire. Not that it wouldn’t work, mind. But they’re living on your skin, so you don’t really want to apply fire. Instead, you apply neurotoxins.

Yes.  Neurotoxins.

The most common over-the-counter medicines for head lice are pyrethrins, which kill by “targeting the nervous systems of insects”. Specifically, “pyrethrins delay the closure of voltage-gated sodium ion channels in the nerve cells of insects, resulting in repeated and extended nerve firings. This hyperexcitation causes the death of the insect due to loss of motor coordination and paralysis.” So, yes. You’re consigning the little bugs to a slow and agonizing death. But it also functions as an insect repellent, driving survivors from the treated area – sort of the over-the-counter version of displaying your enemies’ heads on pike, I guess.

Note that pyrethrins can affect humans, in sufficient doses. The EPA recommends different daily oral exposure limits for pyrethroids of anywhere from 0.005 to 0.05 mg per kg per day (depending on the specific pyrethroid), and OSHA has set an occupational exposure limit for a standard work day of 5 mg per cubic meter. Note, however, that most lice treatment shampoos run around 0.33% pyrethrins by weight. What does that mean?

well, I weigh 133.35 kg, meaning that my safe limit for daily oral exposure to pyrethroids ranges from 0.66675 mg to 6.6675 mg per day, depending on the specific pyrethroid. Assuming the specific pyrethroid in the medicine is the one in the 0.005 mg per kg limit, I could drink 202 mg of the medicine and generally be all right. (Note: do not do this!) That’s not a whole lot, though, which is why these medications fall under the category of “safe when used as directed“.

Head lice medication cocktails are not a use as directed.

What Do Lobsters Do?

A while back, we were out grocery shopping. My son really enjoys this (sometimes) because I let him get involved. He gets to pick out some of the fruit we buy, and he asks questions, and he gets to go look at the lobster tank. This last part is huge for him, because the lobster tank at the local grocery is a big cylinder sitting out in the aisle. And it has benches next to it, so you can sit and look at the lobsters. Or, if you’re five, so you can climb up and press your face to the plexiglass and stare at the lobsters in fascination. I’ve told him that they’re there so people can buy them and eat them, but he still regards it as a huge aquarium.

So we’re sitting and looking at the lobsters, taking a short break before we get back to the shopping. And he’s tapping on the glass, and staring at the lobsters, and asking questions. “Why are they in there?” “Why do they have rubber bands on their hands?” Things like that, easy questions.

“What do lobsters do?” he asks.

What? What does that even mean? So, I ask him. “What do you mean?”

“What do lobsters do?” he repeats, his voice incredibly patient.

“Like, what do they eat?”

“No, daddy,” he repeats, enunciating. “What do lobsters do?”

That’s a pretty heavy question. Let’s see if I can’t answer it.

What is a lobster?

Let’s start at the beginning. What, exactly, is a lobster?

lobster

This. This is a lobster.

Sure, I’ve seen pictures of them. And I’ve seen them in grocery stores, and at the aquarium. And that’s about as far as my knowledge goes. I think I’ve always assumed that they were oceanic bugs, maybe related to crabs, and then I went on with my day. They never really caught my attention the way dolphins or sharks or cuttlefish ever did.

The answeer is a bit tricky.

See, lobsters are crustaceans, a class of creature defined by the Encyclopedia of Life as belonging

to the phylum Arthropoda, as do insects, arachnids, and many other groups; all arthropods have hard exoskeletons or shells, segmented bodies, and jointed limbs. Crustaceans are usually distinguishable from the other arthropods in several important ways, chiefly:

  • Biramous appendages. Most crustaceans have appendages or limbs that are split into two, usually segmented, branches. Both branches originate on the same proximal segment.
  • Larvae. Early in development, most crustaceans go through a series of larval stages, the first being the nauplius larva, in which only a few limbs are present, near the front on the body; crustaceans add their more posterior limbs as they grow and develop further. The nauplius larva is unique to Crustacea.
  • Eyes. The early larval stages of crustaceans have a single, simple, median eye composed of three similar, closely opposed parts. This larval eye, or “naupliar eye,” often disappears later in development, but on some crustaceans (e.g., the branchiopod Triops) it is retained even after the adult compound eyes have developed. In all copepod crustaceans, this larval eye is retained throughout their development as the only eye, although the three similar parts may separate and each become associated with their own cuticular lens. In other crustaceans that retain the larval eye into adulthood, up to seven optical units may develop.
  • Labrum. Crustaceans have a lobe-like structure called the labrum anterior to the mouth that partially encloses it.
  • Head. Crustaceans are distinguished by a five-segmented head (cephalon), followed by a long trunk typically regionalized into a thorax and abdomen.
  • “Baby teeth.” Most crustaceans in their early larval stages chew their food with a unique structure called a naupliar arthrite, which is on the second antenna. This chewing tool is lost later in development, and chewing is taken over by the mandibular gnathobase.

Wikipedia adds that crustaceans include crabs, lobsters, crayfish, shrimp, krill, barnacles, and “all animals in the Pancrustacea clade other than hexapods” (with hexapods meaning insects). So, you really could argue that lobsters are bugs. They’re just not insects.

But wait! It gets even more complicated!

True lobsters are part of the Nephropidae family. They’re part of the Animalia kingdom (making them animals), the Arthropoda phylum (meaning they’re invertebrates with exoskeletons and segmented bodies), class Malacostraca, order Decapoda (meaning “ten-footed”). At present, fourteen different genera of Nephropidae are known, with a total of 54 different species. Out of those, if you’ve eaten one, it was most likely Homarus americanus (the American lobster, found on the Atlantic coast from Labrador to New Jersey) or Homarus gammarus (the European lobster, found along the eastern Atlantic coast of Europe, as well as the Mediterranean and Black Seas).

Related Decapodae are the spiny lobsters (family Palinuridae), the slipper lobsters (family Scyllaridae), furry lobsters (family Palinuridae), and squat lobsters (which are actually more closely related to hermit crabs). None of them are considered to be true lobsters.

Great. So what does a lobster [do?

There’s 54 different species, each of which does its own thing. In general they are benthic omnivores, meaning they live on the sea floor and eat whatever they can find. Fish and mollusks make up the majority of their diet, but they’ll eat algae, sea plants, and even other lobsters if they need food – although cannibalism appears to be a response to population pressures and is not believed to be a primary strategy. As benthic animals, they primarily walk (using eight of their ten legs for locomotion). They can swim as well – backwards – as an escape mechanism if needed. Swimming speeds of up to 11 mph (17.7 kph) have been recorded.

Lobsters, like most crustaceans, have to molt (shed their exoskeleton) in order to grow, something which is part of their reproductive cycle – males and females mate after the female has molted and while here carapace is still soft. The female stores the sperm for up to a year before fertalizing and laying eggs, which she will carry curled in her tail her tail for another 9 to 12 months before they hatch. At hatching, the female uncruls her tail and allows the surviving eggs to be exposed to the water so the larvae can float free.

Larval lobsters are planktonic, swimming near the surface as they go through three stages of development (named stages I through III). Stage III ends with the third molt, when the post-larval lobster finally resembles a lobster and settles down to the sea floor. The young adult lobster spends much of its time hiding and feeding at night, when predators are less likely to find and eat it. As they age and grow, they travel further to feed and begin to stake out a territory. Then, once they reach sexual maturity, the process starts over.

So, what do lobsters do? Pretty much what all other animals do: eat, sleep, grow, and breed.

Do Earwigs Go In Your Ear?

As we generally do, I let my son pick out his bedtime story. He chose Once There Was a Tree, which turned out to be a fascinating little story about a tree getting cut down and then all the different animals that made use of the stup for various purposes. Quite well done, and the art is mostly extremely good. But there’s one passage that reads:

The warm sun dried the tree stump, and soon a new occupant had moved in – an earwig. Liking nothing better than the shade, he crept under the bark to sleep.

First, my son asked me what an earwig is. I had no idea, and the illustration in the book didn’t make it very clear. Second, my son – riffing off the name – asked me if earwigs go in your ear. Without knowing for sure, I said “no”. There are just some things you don’t want your five year old thinking about too hard right before bed. But I have no certain knowledge that this is true. So, here we go.

To begin with, this is an earwig:

earwig2

So, yes. That picture, combined with a name like ‘earwig’, is terrifying. Wehn you dig into the meaning of “earwig”, it doesn’t get any better. According to Dictionary.com, the name comes from the “Middle English erwigge, Old English ēarwicga ear insect; from the notion that it enters people’s ears”.

According to the PennState College of Agricultural Sciences Department of Entomology, there “are twenty-two species of earwigs in the United States, twelve of which have been introduced from other countries”. Their article focuses on the European earwig (Forficula auricularia), which is “considered one of the most important earwigs since large numbers of them may seek shelter in homes and consequently become a notorious household pest”.

The European earwig was introduced to North America some time in the early 1900’s, and was first observed in the United States in 1907. They tend to be 5/8 inches long, with forceps ranging between 3/16 inch and 3/8 inch. Those forceps are used both for protection and to capture prey. They can fly, but rarely do, and they prefer to hide in dark, most crevaces. They’re omnivorous, eating most any plant matter and other insects.

Iowa State University, on their Earwigs page, addresses the question of whether or not they crawl into human ears:

Earwigs are a fairly well-known insect, from folk lore if not from actual experience. The earwig is the insect reputed in superstition to purposefully crawl into the ears of sleeping persons for the purpose of burrowing into the brain to lay eggs. Of course, there is no truth to these tales, though earwigs, like moths, beetles, cockroaches, ants and flies may wander into our ear canals by accident.

So, they might. But if they do, it won’t be any more deliberate than any other insect that crawls into your ear. I’ll leave it up to you to decide how comforting that is.

But if they don’t crawl into your ear so they can burrow into your brain and lay eggs, are they dangerous? The short answer is, “not terribly”. Not to people, anyway. Orkin, a pest control company here in the United States, has this to say on the subject:

Many people wonder if earwigs will bite people. The pincers are used for defense and if picked up and agitated, the earwig will exercise the use of the forceps. These are not stings or bites, though, which are terms used for insects with stingers or biting mouthparts. Even in extreme cases of large forceps of adult males, the pinch can be painful but there is no venom and the pinch rarely breaks the skin.

In the event that the pinch does break the skin, it is best to utilize the same first aid as one would use for any type of scratch. Keep in mind that earwigs do live in the soil typically, so there is the possibility of germs getting into the cut from the forceps. So, if there is a cut or open sore, or if the earwig pinch breaks skin, use a proper antibiotic lotion or cream. There is no telltale “bite mark” unique to an earwig as they do not hurt people. If there are medical concerns, speak to a medical professional.

So no, they don’t bite. They’ll just shank you with their tail pincers if you pick them up. And they won’t burrow into your brain through your ear. So really, you can stop worrying about that and start worrying about the eight spiders a year that it is claimed you eat in your sleep.

That’s not true either. But try and convince yourself of that tonight.

What Eats Spiders?

One odd little tradition I have with my son when I pick him up from preschool is the “tickle spider game”. It goes like this. He climbs up on the railing that runs down the sidewalk, and begins scooting along it. I put my hand on the railing behind him and scurry it after him like a bug, all while shouting “tickle spider’s gonna get you!”. He laughs, and makes it to the end of the railing and declares it base. Then, if traffic is clear, he sprints to the car while I pursue him. “Tickle spider’s gonna get you!”

It’s silly, yeah. But it’s evolved into a thing we do.

One day, after we do this and I’ve got him belted into his booster seat, he starts telling me about how some spiders have big, hairy heads. I’m not positive why this comes up, but spiders are on his mind because of the game. And I think that someone may have brought a tarantula into his class as well, so he’s thinking about big, hairy spiders at the moment. And then he asks his question:

“What eats spiders?”

Well, I can answer that in part. So I tell him that bugs eat spiders, and birds, and frogs. He answers “no”, and proceeds to tell me that dogs eat spiders. And then he’s off talking about Luke Skywalker, because he’s five.

So what *does* eat spiders? The answer, according to a few different web sites, along with Rainer Foelix’s Biology of Spiders, the answer seems to be “lots of things”. This includes the usual suspects – frogs and toads and lizards and birds and insects – and a few that I never once thought of as preying on spiders. Monkeys, for instance. Or other spiders. Ants as well, which just gives me a horrible mental image of a swarm of ants rolling over a spider and tearing it to pieces (fair warning:  don’t click that link if you’re afraid of spiders, or of ants). But two spider predators really stand out. The assassin bug, and the spider wasp.

This is an assassin bug:

wheel-bug_ed

An assassin bug hunts by finding a spider web. It then begins plucking the web in a pattern that simulates struggling, exhausted prey. When the spider comes to investigate the assassin bug gets into position and stabs it with its proboscis, injecting either venom or digestive acids (depending on the species). Once the spider dies, it settles down to dinner.

They’ll also bite people. The bug is too small to kill a human, but the bite does transmit a parasite called Trypanosoma cruzi, which is responsible for something called “Chagas disease“, most commonly encountered in Latin America. The parasite results in skin lesions and/or purplish swelling of eyelids, fevr, headache, enlarged lymph glands, muscle pain, abdominal or chest pain, and difficulty breathing. If left untreated, it can also result in death from destruction of the muscles and nerves of the heart.

So, yeah.  Maybe they can kill humans.

And then there’s the spider wasp:

spider wasp

“Spider wasp” is actually a common name for the Pompilidae family of wasps, consisting of around 5,000 species. Why are they called “spider wasps” you ask? Well, you may have heard about this before, but spiders are an important part of their reproductive cycle. The spider wasp female digs a burrow, then locates a spider. She paralyzes the spider by stinging it, then drags it back to the burrow and lays an egg on it. The paralyzed spider is then stashed in the burrow, where the egg hatches and the wasp larva consumes it.

Not all spider wasps dig burrows, though. Some will just paralyze the spider and let it lie, with the egg on it. Either way, it sucks to be that spider.  But hey, at least there’s no evidence that dogs will eat them.