Questions from the Botulist

Dear Antboy,

I’m quite fond of Ants on a Log, but glad the ants are raisins and not real ants. Have you ever eaten an ant or any other insect? Are there any other tasty snacks or meals that are named after an insect?

Love,
Kimbot

Well, there’s a strong school of thought in field biology that you should taste your research animal so you know what the predators that go after it are tasting. I have indeed tasted various species of Cephalotes ants, and I can state pretty confidently that they are not particularly good. They have a really, really nasty alarm pheromone that they spray when they think they’re getting eaten, and besides telling all their friends in the area that something is trying to eat them, it also tastes absolutely awful.

I’m not alone in this opinion, either, as Cephalotes ants don’t tend to have a lot of natural predators that go after them specifically. However, despite the fact that most things don’t want to eat them in their normal state, they do have a very cool nematode parasite that my friend Steve Yanoviak discovered that turns their abdomen/gaster bright red:

(photo: Steve Yanoviak)

This encourages birds to bite off the infected gaster, under the impression that it’s a tasty berry and not a big old bag of nematode eggs. Once tricked, the eggs pass through the bird, the bird poops somewhere, the ants eat the poop, and the nematodes find a new host, completing the cycle. I have not tasted the nematode infested ant. I have to draw the line somewhere.

As for insect-themed food items, I’m drawing a bit of a blank at the moment, but maybe people will help me out in the comments…

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Question from a sentient Venus flytrap

Dear Antboy:

Ants are so tasty. Does anything there eat ants in strange and unusual and cool ways?

Dionaea muscipula

Wow, this blog sure is attracting its fair share of eccentric readers – this latest question was signed by Dionaea muscipula, more commonly known as the Venus Fly-Trap. I haven’t seen much in the way of your carnivorous plant friends around, and truth be told most things around here seem to eat ants in more or less the usual way (i.e. stuffing ant into mouth, chew, swallow), but one particularly common mode of ant demise that you might find appealing is that of the parasitic fungi of the genus Cordyceps. If you haven’t heard of these before, you should immediately go watch this video, taken from Planet Earth:

Like Mr. Attenborough says, each species of Cordyceps specializes on a single species of insect, and different species of Cordyceps can look very different from one another. Here’s a Cordyceps species that specializes on Cephalotes atratus:

Cephalotes atratus w/ sprouted Cordyceps

and here’s a different species that goes for Pachycondyla villosa:

IMG_3939

The fruiting bodies are the little translucent red ovoid sacs on stalks. One’s coming out from her trunk, but there are many more on her abdomen/gaster:
IMG_3944

Interestingly, this ant is still alive despite the presence of many fruiting Cordyceps bodies. Probably not for too much longer, though.

IMG_3954

I’ll keep an eye out for other things eating ants in unusual ways, though, and if I find anything I’ll let you know.

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Questions from Dennis and Mace Windu

I got a couple questions about measuring wind turbulence, one from my labmate Dennis:

What is turbulence and how do you measure it?

and the other from, uh, Mace Windu:

Dear Antboy:

I heard you were going to measure wind somehow. How is that working for you?

Mace Windu

I have a sneaking suspicion that both questions may have originated from the same source, as Dennis is probably about the only person I know who would actually try to impersonate a character from justly reviled Prequels. Either that, or Ron Perlman pointed his friend Samuel L my way.

Anyway, my labmate (and fellow blogger of invertebrate field biology) Lindsayalready wrote a post about how she’s measuring turbulence in Moorea (an island just off of Tahiti), and what I’m doing is largely similar over here, equipment wise.

Basically, the idea here is that we’re curious about how windy conditions might affect the ants while they’re gliding. That is, if an ant is falling and trying to glide back to its home tree and a gust of wind happens to blow by at just that moment, does she get blown away with the wind or can she compensate? We’re also interested in how the ants deal with different levels of turbulence, which is roughly a measure of how variable the speed and direction of the wind is at a given point in space.

Now, ideally, what I’d love to be able to do is to measure what the air is doing over the entire volume of space through which the ant is gliding. Unfortunately, that’s kind of hard to do, and so what I’m settling for at the moment is measuring what the wind is doing at one point halfway up the tree while I drop them and film their glides. Now, obviously the further the ant is from the point where I’m measuring the wind speed and direction, the less confidence I have that what I’m measuring is what the ant is experiencing, but we’re going to go ahead and sweep that inconvenient little fact under the rug for the time being.

I’m measuring wind speed and direction using a 3-D ultrasonic anemometer, which looks like this:

Those little black arms in the middle are ultrasonic transceivers, which means that they can both emit ultrasound pulses and receive them. To measure wind speed, transceiver A shoots a pulse at transceiver B, and then transceiver B shoots a pulse at A. If the air between them is moving, there will be a difference in the time of flight of the two pulses, and that time difference can be used to calculate how fast the air is moving. Then, by using three pairs of transducers at right angles to one another, you can measure the wind speed and direction in 3D.

Today I set up this anemometer at a height of 15m above the forest floor, while I was dropping ants from a height of 20m. The ants will typically get back to the tree within 10m if they’re dropped about a meter and a half from the tree, so this is a reasonable halfway point. Today was a very gusty day (the data below are the precursors to a huge storm that rolled through today), and the data from about 40 minutes of sampling looks something like this:

The direction of the wind also changed with time, as shown in this plot which shows the azimuth (horizontal angle, like compass direction) and zenith angles (angle away from vertical, where zero implies that the wind is blowing horizontally) of the wind direction and how those angles change with time. The azimuth is shown in blue, and the zenith is shown in green:

I dropped a bunch of ants, some during the lulls between gusts where the wind speed was around 0.5 m/s, and some during the gusts (which sometimes got to be over 3 m/s). Somewhat unsurprisingly, it looks like when you drop an ant into a gust, it’s harder for her to get back to the tree trunk, and if the gust is strong enough she won’t make it back at all. Once I analyze the trajectories, I’ll be able to say how those trajectories are influenced by wind speed.

However, I do want to point out that I picked this tree specifically because it’s more exposed than most trees in the forest, and I was interested in looking at this question. Most of the time, it’s not very windy underneath the rainforest canopy – wind speeds are usually around or under 0.2 m/s, which is barely detectable.

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Mail from the Revenge

Dear Antboy-

I am curious about the lifespan of ants – in particular your gliding ants. Can you describe what life is like for worker ants and how long they are subject to hard labor? I would also like to know about the queen. How many times does she have children before she throws in the towel? Does she ever get a vacation from child rearing?

Thank you for all the great information! I never knew ants were so interesting.

-Yar’s Revenge

Dear Ms Revenge –

I’m actually not sure about the exact lifespans for the Cephalotes ants, but I’ll take a look into it when I get back from Panama and see what I can dig up when I have some library access. In general, though, the workers of any ant colony are short-lived compared to the queen. In fire ants, for example, the workers will live for between 10 and 70 weeks, whereas the queen will live for 6 or 7 years (according to Table 3-3 in The Ants, by Hölldobler and Wilson). Carpenter ant workers can live for several years, and queens can live up to fifteen years or so. The queens of some species are estimated to live for up to thirty years. I would guess, based on the fact that the workers are large and expensive to manufacture for the colony, that Cephalotes atratus workers would end up being on the more long-lived end of the spectrum, but I don’t have a specific number just yet.

As for what the workers do, in the beginning of their lives as adults, their first job is tending to the larvae of the nest. This mostly means feeding them with the food that the foraging workers are bringing in. After they finish their nursing period, their job becomes bringing home the food. Every day, they will be out and scavenging for solid food, like bird poop and dead things, as well as looking for liquid food like nectar. Often I’ll find them camped out on trees that have extrafloral nectaries, like Inga trees. These trees have additional nectar producing structures (aside from flowers, which is where you typically find nectar) that are usually found along the stem of a leaf. It’s thought that the trees have these specifically to attract insects, with the point being that insects that come to feed on the nectar will drive away more damaging herbivorous insects that are more interest in chewing up the tree’s leaves, which the tree obviously would prefer not to have happen.

That said, it’s not all hard labor all the time. A lot of the time, when ants aren’t out foraging, they’ll just be hanging out in the nest apparently not really doing much of anything.

As for the queens, your question is exceptionally well timed as some friends on the island recently brought me a Cephalotes atratus queen that they found out in the forest.

IMG_3887

There are more photos on the other side of the link, if you’d like to get some other views of her. She’s about 20mm long, so about a third again as large as the workers. I don’t have any reason to expect that she should be able to glide like the workers, partly because she’s so much heavier than the workers while having relatively short legs for her size, and partly because for the most of the motile part of her lifespan she has wings that she uses to get around on. But if I have time I’m going to try and chuck her in the wind tunnel just to see what she does.

As you can see, she’s already dropped her wings, but if you look at the full size version on the Flickr page you can see the stumps from where they used to be attached. The fact that she’s dropped her wings means that she has already mated and is ready to try and found her new colony. The queen will never re-mate – she mates only once, and stores all of the sperm from that mating in a gland called the spermatheca. She will then use these sperm for the rest of her life to produce all of the workers for her colony, as well as all the reproductive winged males and females when the colony goes into a reproductive cycle. So, depending on the species, a single queen will lay thousands if not millions of eggs in her life. And as far as I’m aware, no, she never really gets much of a break.

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More gliding ants

Dear Antboy,

I tried to make a gliding ant out of paper like you said. I think I got the face more or less right, but I’m not so sure about the rest of it. His name is Gerald, but he doesn’t glide very well. Could you please give me some pointers on how to make him better? Here’s a picture so you can see what he looks like now:

Thanks!
Jose Jones

Dear Jose –

That’s a great looking start you’ve got there, and I agree, the face is looking pretty tops. I think I’ve got a few suggestions that might help out with Gerald’s aerodynamics, but there’s a change Gerald is going to have to go through before we work on any structural issues. You may wish to ask Gerald how he feels about the name Geraldine, as he’s going to have to become a she.

You see, all gliding Cephalotes worker ants are girls. And if you’re wondering how one tells a boy ant from a girl ant, it’s actually pretty easy in practice – generally, if you’re holding it, it’s a girl. For most of the lifetime of an ant colony, there are no male ants around. There is (usually) a single queen ant whose job it is to lay all the eggs that become workers, and then there are lots of worker ants who are all female and usually sterile. Then, at certain times during the life cycle of the colony, the colony of ants goes into a reproductive phase and some of the eggs laid by the queen become reproductive males and others become reproductive females. The males are not particularly helpful members of the colony, and exist only to engage in large mating swarms with the reproductive females. Once they’ve mated, they die soon after.

Yes, yes, now would be an excellent time to collect all of those awesome joke ideas you just thought of and write them all down. It’s okay, I’ll still be here when you get back. For the rest of you, here’s your basic worker ant, that does all the hard work around the colony:

IMG_7255

This is a pretty common species of ant here in the tropics, named Ectatomma tuberculatum.

Now, you may be wondering what these useless males look like, and the short answer is: weird. Colloquially referred to as ‘flying sperm missiles’, male ants tend to have pretty minimal equipment besides gonads and a set of wings. Here’s a male Ectatomma tuberculatum for comparison to the worker above:

Ectatomma tuberculatum male

And here’s a shot from the side:

Ectatomma tuberculatum male

Few things to notice here:
1) Wings. If you weren’t previously aware that male ants had wings, don’t worry, you’re not alone.
2) Big old abdomen (or ‘gaster’, to use the correct term that no-one who doesn’t study Hymenoptera knows).
3) Teeny little head with wimpy little mandibles.

So let’s start with the big one, i.e. the wings. Now, those of you who spent a few minutes earlier drawing parallels between your own life experiences and the differing roles of males and females in ant colonies might now be having a hard time with this, in that the males are not only completely useless and do no work, but also get sweet wings. But it’s okay, the reproductive female ants get wings too. Here’s a picture of a Pheidole female reproductive ant that landed on me in the dining hall the other day:

Pheidole alate

But aha, you may be saying, this ant clearly has no wings. Here’s the cool part: she did have wings at one point, and you can see where they used to be attached on her thorax there if you look closely. The reproductive alate females (alate being a fancy word for ‘with wings’) leave the colony, find a bunch of males, mate, and then try to find a nice place to start a new colony. At that point, she’ll drop her wings off and internally digest her flight muscles, using that energy to raise the first brood of workers that will help her set up her new colony. Or at least, that’s how it’s supposed to work; most of the time things don’t really work out and the young queen ant ends up getting eaten.

Anyway, so that was a long-winded digression to help explain why your ant Gerald isn’t really a boy, but we haven’t really helped out with Geraldina’s aerodynamics yet. Now, as I mentioned earlier, the facial detailing is top notch, but one of the things you’re missing at the moment is legs, which turn out to be pretty important if you’re a gliding ant. Now, recall from last time that your basic gliding ant looks a little like this:

C. atratus

Pretty, yes, but it’s not immediately obvious how something like this ends up being a glider. That is, she doesn’t have any obvious wings or wing-like things sticking out of her that look like they might be useful for gliding. So, in an effort to try and learn a little about how these ants glide, I’ve been doing experiments where I toss them into a wind tunnel and see what they do. It turns out that their standard gliding posture looks a little like this:

Gliding C. atratus

See how she’s holding her legs outstretched and above her body? What she’s doing there is basically making a little parachute out of her body, by putting the parts of herself that have little mass but lots of surface area (i.e. her legs) above her heavier parts that have more mass per unit of area (i.e. her abdomen). I’ll go into how all of this works in a future post on the aerodynamics of stability and control in human parachutists and gliding ants, but for now you should have a few more ideas on how to help Geraldine be a better glider. Try adding some legs, and bending those legs up and outward from the body. Now when you drop Geraldine, she should at least always fall right side up when she falls. To see how important leg position is, try bending her legs in the opposite direction and see what happens. Then, just for kicks, try bending them up on one side and down on the other. It’s fun, trust me.

Also, for those still having fun with the whole bugs vs insects thing, here’s a couple cool bugs I found running around. This guy here my friend Steve found for me up in the canopy – he’s actually a gliding wingless bug, and hopefully I’ll get some time to throw him in the wind tunnel:

Bug

And then here’s another Reduviid bug (that is, one that preys on other insects), this one being a thread-legged bug. When I found this guy, I thought it was a mantis due to the way it was holding its forelegs, but under the macro lens it revealed itself to be a bug. Any ideas on how you can tell this guy’s not a mantis?

Thread-legged Bug

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A letter from Ron Perlman

Dear Mr. Fancypantsscienceguy,
You seem to know a lot about bugs. that’s cool. I’d like to know more about red bugs. Red bugs look the best!

Have you ever been bitten by anything really really badly? Do any bugs scare you at all?

Your head is very large, and that’s a-ok.

– Ron Perlman

Dear Mr. Perlman –

Well, I can’t tell you how excited I am to hear from one of my cinematic heroes so soon after debuting my blog; I would have done this long ago had I known!

After getting your mail, I went out in search of some nice red bugs for you, but sadly I haven’t come across any really, really red ones yet. I’ll keep an eye out, though. In the mean time, here are some non-red bugs I found:

Assassin Bug

Assassin Bug

Now, Mr. Perlman is no doubt already familiar with the subject material to follow, but there may be some of you out there thinking to yourselves ‘Hey genius, those leaf-cutter ants you posted about were redder than either of these two guys’, but if you’re one of those people thinking that there’s a long and involved and also boring entomological technicality at play here that I intend to waste your valuable time with presently.

There are lots and lots of insects. Like, lots. Estimates vary, but there are about a million described species and anywhere from two to thirty million species that have not yet been described. If this sounds like a big number, it’s because it is. By way of comparison, there are about 5400 known species of mammals.

It is certainly popular to refer to just about anything small and crunchy as a ‘bug’. In polite conversation I’m generally just about as happy as anyone to do the same, and I even enjoy calling what I do ‘bug-chucking’. However, this being The Mighty Intertubes and given that the eyes of the Hemipteran Crusaders may be watching, I am duty-bound to inform you at this juncture that this is technically incorrect.

Not a bug.

There are many kinds of insects, and only some of them are actually bugs. The ‘true bugs’ belong to the order Hemiptera, and include things like cicadas, aphids, water striders, and the assassin bugs pictured at the beginning of this post. All told, the order Hemiptera contains about 80,000 described species, and all bugs (at least to my knowledge) eat using piercing and sucking mouthparts. That is, they have a sharp beak that they stick into stuff so that they can suck out all the good things inside. This is often not a good thing for the food item in question, which is why gardeners are generally less than fond of aphids.

IMG_7236

Also not a bug.

So, to recap:
– Not all small, crunchy things are bugs
– Not all insects are bugs
– Only a certain kind of insect is a bug

Molting cicada

A cicada, which is a bug.

Now, you may be thinking that this is all really kind of pedantic and annoying, to which the short answer is: welcome to entomology (and taxonomy in general, for that matter). And as I mentioned, I personally don’t really have a big deal with the whole colloquial use of the word ‘bug’ to refer to all insects (I draw the line at calling spiders ‘bugs’, however).

Basilisk Lizard

Really, really not a bug.

But if you’re having a hard time understanding why anyone would care, let me attempt to make a sporting analogy. Say, for example, you were a fan of some sport. For the sake of argument, let’s pick, oh, ice hockey.

And say that you happened to be particularly fond of one of the teams that plays ice hockey. Just for the sake of argument, let’s go ahead and say that your team is the Detroit Red Wings.

But then let’s say that people generally didn’t know a lot about ice hockey or the teams that play professional ice hockey, and that colloquially everyone called all hockey players by the name that is technically used to describe a different team. Like, say, the Toronto Maple Leafs.

And so you’d be hanging out and watching your beloved Red Wings play ice hockey, and then some people who weren’t perhaps as well informed about ice hockey would be all, ‘Hey, check out those Toronto Maple Leafs playing ice soccer!’ or some other entirely plausible phrase. You get my point. Anyway, I can imagine that there may be some readers out there for whom such a situation might be considered infuriating if it happened all the time. And so it is, I guess, for some entomologists.

Not helpful.

So, that concludes our lengthy side note on Bugs vs Insects. Now that we’re all on the same page, you’ll no doubt be pleased to know that the two images presented at the beginning of this post are, in fact, True Bugs in the order Hemiptera. They are members of the Hemipteran family Reduviidae, and unlike many of the other true bugs which feed on plants, the assassin bugs are predators.

Warning: paragraph includes stuff of nightmares. The assassin bugs hunt by sneaking up on other insects and stabbing them with their long, sharp beaks. They then pump digestive saliva into the unfortunate insect prey, dissolving its insides. Then, the assassin bug sucks out the newly dissolved guts.

This incidentally brings me to the second part of Mr. Perlman’s letter, regarding insects I’m afraid of. Assassin bugs are not a bad choice. While something the size of a human is not in danger of having their entire insides liquefied by an assassin bug, their bites are often really nasty and painful, and as a little icing on the cake a number of species will give you Chagas disease in the process, which is well worth avoiding if possible.

I haven’t ever been bitten by an assassin bug, and I’m hoping to keep things that way.

As for painful bites I have gotten, nothing really springs to mind. I did once get stung by a whole bunch of caterpillars while I was climbing a tree, which made my knee swell up like a cantaloupe and hurt a lot, but that’s not really being bitten. But rest assured, Mr. Perlman, when I do get bitten really badly by something, you’ll be the first in line to know.

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A letter from Abber

Dear Antboy,
I see in your About photo that you have bare feet. Is this because you don’t have any shoes? Do you worry about stepping on something sharp? Don’t your feet get cold?
I like to knit. Would you like me to make you some socks?

Abber

Dear Abber –

Despite the bare feet in that particular photo (here’s a close-up, so you don’t have to go squint at the about page):

I am pleased to inform you that I do in fact own shoes. Some of them are mountain adventure sandals, which I think are quite attractive! But that picture was taken in Peru, and it was boiling hot that day. I would normally be worried about stepping on sharp things, but I’d been walking around enough in bare feet to build up nice, thick, gnarly calluses so not much could get through.

But it’s funny you should mention socks, as I’m a big fan of them. I would love some nice knitted socks, please.

antboy

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