Dispelling the aura of danger around spiders

I keep telling everybody — spiders aren’t as scary/dangerous as you think. Now I have a paper that quantifies the risk of deadly spider venom. It’s low.

• The increasing popularity of pet arachnids urges some governments to take protective steps to prevent serious envenomations.

• A literature review was carried out to assess which arachnids can be classified as potentially dangerous.

• About 0.5% of all spider and 23% of all scorpion species were classified as potentially dangerous.

• Even envenomations from the most dangerous arachnids have a low percentage of serious or even fatal consequences.

• We conclude that the public threat from pet arachnid envenomations has been overrated.

Here’s the list of potentially dangerous genera.

Note that the list errs strongly on the side of caution. It lists Eratigena, the hobo spider, but says in the text that “there is not a single verified bite that confirms E.agrestis or other members of this genus as dangerous to humans”. Latrodectus, black widow spiders, do have a real record — 23,000 incidents reported over 8 years — but less than half of those cases involved envenomation, and only about 1% exhibited severe effects, and there were 0 deaths. The Parasteatoda and Steatoda species I work on are only briefly mentioned and dismissed because their effects are much weaker than those of Latrodectus.

I’ve also never encountered any of the spiders they list, and I’ve been looking. I guess if I lived in Malaysia or Brazil I’d experience more of the thrill of danger, but here in Minnesota we’ve got a non-existent concern, and even in those tropical countries it’s a relatively minor worry.

(Of course I learned about this paper from Gwen Pearson. It’ll be useful if anyone at the university expresses concern about the hundreds of spiders currently in my lab.)

’tis the season

My spider family is going mad, spewing baby spiderlings everywhere. I came into the lab today just to maintain and feed the several hundred hatchlings I’d acquired over the past few days, and what do I find? Another egg sac has opened up, and another hundred or more babies are begging for attention.

Yeah, yeah, I was a responsible parent, and I separated out as many as I could and put them into nice clean vials. I’m reaching capacity, though. This means I have about 300+, maybe as many as 400, itty bitty Parasteatoda offspring in my lab, packed into two incubators. Looking ahead optimistically, I can maybe accommodate 60 adults in the lab, if I pair up males and females. It feels weird to say it, but I’m good if I have 80% mortality in the babes.

I suppose if they thrive I can just turn the majority loose in my basement.

Hungry hungry spiders

All these baby spiders hatched out over the last few days, and I had to start feeding them. I’ve got a lot of flies, I opened each vial one by one, and tossed in a surprised wingless fly. All the babies, even though they’re only two days old, had strung silken lines all over the place — baby’s first death trap! — and were waiting patiently, hanging upside down like the grown ups, and wow, were they ever excited when the first fly was snared!

Here’s a pair of Parasteatoda juveniles, literally seconds after I put a single fly in. They descended on it immediately. Baby’s first kill!

I’m about halfway through the feeding. It’s starting to go faster as I get better at manipulating massive numbers of flies. The Runestone line is all completely fed now, with the corpses of their twitching prey piling up. I think I’ll take a break and feed the remainder tomorrow.

SO MANY SPIDERS!

Yesterday, one Parasteatoda egg sac popped and sent out a cloud of baby spiders I was struggling to corral. Today, another hatch!

I’m going to be here in the lab for a while. I have to separate these out into individual vials and feed each of yesterday’s spiders. It’s hard work being the Mother of All Spiders. I hope I’ve got enough flies.

Sorted, sorta.

I estimate there are about 160 spiders in all those tubes. I couldn’t possibly put single individuals in each, I don’t have enough space — so there are two or three in each, with 8 or so in the larger cube-shaped containers. I found an efficient way to move them. I’d just hold the container with the whole clutch at a slight vertical angle, and the babies would make their way to the edge and leap off, rappelling downwards, and I’d lower them on their threads into a tube and brush the silk against the lip, and then cut them off with a sponge. It worked well enough that I had no accidents that I noticed, which in part accounts for the larger numbers here over the previous day’s catch.

These, by the way, are called the H line because I caught the mother and egg sac at the Horticulture Display Garden. Mom is fine, she’s in one of the containers, too.

Both of these clutches are from wild-caught spiders found outdoors, which troubles me a bit. I’ve definitely got to get at least one batch from indoor spiders — I’ve got some egg sacs like that right now, but I’ve had a very low success rate from their ilk. Maybe country spiders are more fecund than city spiders?

I’d say you can stop asking me these questions now, but I know they’ll continue

I’ve noticed that there are two kinds of responses people make when they learn I’m studying spiders. 1) They tell me about the terrible spider bites they’ve been getting lately, and 2) they ask if it’s true that people swallow thousands of spiders while sleeping in their lifetime. At least now I can cite this definitive response from Andrea Haberkern in answer to the first. Spiders have no interest in biting anyone!

Bite Post FAQs
1. Can anyone tell me what bit me?
Doctors nor entomologists nor arachnologists can ID bites from a bite alone in the majority of cases. There are likely a handful of exceptions, as in the case of some tick bites that have signs but overall this is not the case. So, if a someone tells you “it’s a spider bite” or “it’s a recluse bite” without seeing the animal itself do the biting, chances are it is something else entirely …but, more on that later…

2. What can we do about this bite?
First and foremost- this is a nature appreciation group, not a medical advice group. Medical advice is not allowed by any members. No members, to my knowledge, are medical doctors. If you or a loved one is suffering negative effects from a bite, please seek medical attention.

3. Do you think a spider bit me?
No. The reason for this is boils down to basic spider biology. I would venture to say that the vast majority of “spider bites” are something else entirely. I think many people believe that spiders go around biting sleeping people, falling from trees just to bite you or are sneaking around looking for their next tasty human to chomp on. I’m assuming the reason this is such a common misconception is likely due to a lack of understanding of what these animals are all about. So… spiders evolved venom to eat insects and other small prey. They use it to immobilize their prey. Just like it takes your body a tremendous amount of energy through food intake to conduct daily activities, it also costs spiders a lot of energy to produce this venom. Why would an animal that needs a substance to eat go around wasting it on mammals when it has nothing to gain for it? It wouldn’t. Now, I’m not saying spiders never bite. Any animal with a mouth can bite. If you grab a spider, I bet it will bite you- just like if you grab a squirrel it will bite you. But I don’t hear anyone saying squirrels are jumping into peoples’ beds while they sleep just to bite them. So why spiders? Spiders will bite in self-defense, but just to add to the unlikelihood of being bit by a spider- most species will do several other defense tactics before resorting to biting. These tactics include: fleeing, playing dead, threat displays, falling to the ground, kicking silk at you and, in some species, throwing poop at you. Biting is an absolute last resort, again because venom is energetically costly and its main purpose is to eat not defense, so you practically have to force a spider to bite you. Just to drive the point home even further- I would place money on the fact that I am likely one of the only people in here who has actually been bitten by a spider. But put that into perspective- I have to manhandle, harass and grab spiders, literally thousands of times, for my work…but even still- I’ve only been bitten a dozen or less times out of thousands of rough handling… I’ve deserved it every time. So, no, I don’t think a spider bit you. Even in cases where a spider was in the general vicinity… false blame is likely to blame.

4. So if a spider didn’t bite me what did?
There are literally hundreds if not thousands of other animals (and plants) that are more likely to have bit you or caused you skin irritations. These include anything that does either directly feed on us or uses bites/irritations as a defense. Examples of organisms that are a way more likely culprit for your skin issues include, but are not limited to: some midges, chiggers, mosquitoes, poison oak/poison ivy, horse flies, sand flies, fleas, stinging nettle, ticks, assassin bug defensive bites, conenose bugs, ant/bee/wasp stings and even some plant/fruit eating bugs that will take the occasional nibble.. etc. etc.

5. But but but I saw 2 puncture holes in my skin, it had to be a spider….
This is a myth. I think it comes from a common misunderstanding of spider mouthparts. Most people assume that all spider chelicerae (fangs) face downward like that of a tarantula and therefore cause 2 bite marks. This is not the case. Only the Mygalomorphs (tarantulas, trapdoor spiders and Aussie funnelwebs) have their mouthparts oriented like this. But seeing that tarantulas and kin are much larger spiders- I think you would physically see if one bit you. So, when someone says “I know this much smaller spider bit me even though I didn’t see the spider because I have 2 bite marks” … there several reasons why this is not the case. First, most spiders’ mouthparts are oriented to meet side to side not parallel facing downward (if the visual is too hard to imagine google image search “Mygalomorph versus Araneomorph mouthparts”) So, if one bit you, a single puncture would be more likely from where the 2 fangs meet. Next, if there were 2 bite marks in the skin caused by a spider- this would have to be a BIG spider for them to even be visible- I highly doubt a spider of that size is capable of sneaking in, biting you without you seeing it, then sneaking away in the night to leave you with only 2 little vampire marks as “proof”. Many many insects will bite multiple times in a localized manner, and considering how much more likely insects are to bite humans than spiders in the first place, that again is more likely your little biting friend.
Spiders rule,
-Andrea

As for the second question…no spider would blithely crawl into a large carnivore’s mouth. Do you also think hippopotamuses lounge about complaining about all the humans who wandered into their gullets while they were sleeping? No. The whole idea is nonsense, and I’d really like to know where that myth started. I’ve been surprised at how many people ask me if it’s true that people swallow 8 (or some other number) spiders a night, when only a moment’s thought would tell you it’s absurd.

P.S. I’ve never been bitten by a spider, but then I only work with little house spiders. They’ve also never leapt into my mouth.

I’m a proud papa!

I’ve been eagerly checking on my colony every day for the last week or two, because I was expecting a happy event. Tonight, it happened! The babies hatched out!

I expect you all to follow the the tradition and tell me how beautiful my baby is.

Well? I’m waiting!

There were somewhere upward of 80 babies that emerged today. This meant I had to immediately separate all of them into individual vials, or in many cases, 2 or 3 babies in a vial (I’ll separate them further later). I was just sitting there frantically plucking up spiders with a paintbrush and popping them into new vials, which was busy enough, but then…oops. I dropped the egg sac. I’m a klutz.

What happened next is that swarms of tiny, pin-head sized spiders were scurrying off to escape, usually taking flight on a thread of silk. So for about 20 minutes I was sitting there with a paintbrush in one hand and watchmaker forceps in the other, squinting into the air of the lab, my hands darting out to snag a nearly invisible strand of gossamer silk with a nearly microscopic dot of a baby spider on it.

I know some of them got away (sorry, lab neighbors — they’re tiny and cute, don’t worry) because even as I was putting everything away to go home I kept finding more strands hanging from my microscope, or from my computer, or from me. Who knows? I might have some on me right now.

I’ve got lots of baby spiders stuffed into my incubator now. Tomorrow I’ll give each one a fly, and I’ll start tracking their development and health.

Note the “R”. I’m calling this my Runestone line, because the mother (in the individual vial) and the egg sac were collected at Kensington Runestone park.

Now for a little dread: I’ve got 6 more egg sacs in the lab. I’m gonna need a bigger incubator and more tube racks.

Grass spiders taking over

Today is the day I dread: I have to go into the lab and scrub fly bottles and do some general clean up. Responsibilities, yo. Shininess will ensue.

Also, we went on a mini-adventure last night, waiting until full darkness fell and then prowled around our house with a UV lamp and headlights. Unfortunately, I was disappointed — lots of active spiders, but they were all grass spiders. Grass spiders are all over the place, and they sort of take over every summer, but I just can’t get excited about them.

Check out the outside of your house — I bet you’ve got lots of funnel webs around with these shy guys hiding within them.

[Read more…]