bugs – Page 32

Cotton candy for blackbirds

Edit: This post was recently included in the 182nd edition of the Friday Ark, a blog carnival focusing on animals of all sorts.

I’m sure we’ve all seen these in our local wetlands, cattail heads that have become all poofed out as winter progresses, like so much cotton-candy on sticks. I’d never given it much thought before, and if I had I suppose I’ve just assumed that the fluff has something to do with the cattail releasing its seeds to the wind, much like milkweed does.

A few weeks ago, my mom bought the book Insects: Their Natural History and Diversity (with a photographic guide to insects of eastern North America) by Stephen A. Marshall. Steve Marshall is a prof at the University of Guelph, where I did my undergrad, and was one of the instructors leading the Ecuador field course that I took. I didn’t spend much time with him (I knew the other prof better), but he was a really nice guy. So I thought it was cool that Mom had got this book, and I sat down to leaf through it. I was primarily interested in the 40-someodd pages of moth plates, and while flipping through those I spotted an image of fluffy cattail heads. Intrigued, I read the plate caption associated with the figure.

Turns out, those fluffy cattail heads you see in the middle of winter aren’t just the cattail doing its thing. Sure, it will naturally begin to loosen the fluff and lose some to the wind. But the cotton-candy formations? They’re the work of a tiny, drab little moth called the Shy Cosmet (Limnaecia phragmitella). Its caterpillars are appropriately known as Cattail Caterpillars. They feed on the seeds of the cattail in the fall and spring, overwintering inside the head as a larva. In late spring they pupate and emerge as an adult moth in early summer.

In order to ensure that they have a secure home for the entire duration of their stay, they spin tiny silken threads that act as a web holding all the fluff inside. The cattail will still loosen its seeds from the stalk to try to spread them on the wind, but the caterpillar’s netting holds them in place. The result is a rather lumpy cotton-candy appearance.

I thought this was all pretty cool, so I did a bit of searching on the web and discovered a post about the Shy Cosmet, made recently, by Gerry Wykes at Naturespeak (he calls Detroit home, so is within my rather broad neck of the woods). In it he brought in a cattail head and gently dissected it to expose the caterpillars hiding within. Now, I suppose I could have just taken him at his word, but I really wanted to go out and have a look for myself. Insatiable curiosity. In the name of science, of course. I brought in two heads for good measure, and opened them up in a tub to contain any wandering worms.

Gerry indicated that it would take a moment or two for the caterpillars to poke their heads out of the fluff, that they wouldn’t be immediately visible. So I sat there and patiently waited. And waited. Nothing happened. No heads, no tails even, not a hint of movement. I’ll admit that they should all be dormant at this time of year, but since he’d had such luck with his coming out as soon as they were warm, I was beginning to wonder if I’d picked a dud cattail head, one that really was simply just loosening up its fluff.

So I started gently teasing apart the clumps. I found lots of what looked to be frass in with all the seed heads. The seeds are tiny, flat and boxy at the end, and brownish in colour. The frass, on the other hand, was gray and round, spherical. There was lots of it, but no caterpillars associated with any of it.

Finally, after standing with my head bent over this dish for many minutes, I discovered one. Only one, just a single, lone, under-developed caterpillar. Perhaps the cattail head had already been picked over by foraging birds and this was the only guy to have survived. Perhaps there never were many to begin with, maybe I missed one or two. But I went through the entire two cattail heads and only found one. By the time I was done, they looked like this:

Here’s the caterpillar. I found him tucked in a clump of relatively undisturbed fluff, nearly comatose. He wiggled a bit when I first picked him out, but didn’t go anywhere. Gerry was describing his caterpillars crawling all over the place, making getting a good photo difficult. Mine was very photogenic.

This is the caterpillar posed with my mom’s finger for scale. He was tiny. Tiny tiny. This is why I wouldn’t be surprised if I missed a couple others, although I was paying close attention. Below is the caterpillar beside a measuring tape. You’re looking at the inches side of the tape. Each one of those black dashes is 1/16″. See? Tiny tiny, it’s not that my mom has big fingers…

I actually found the dried husk of an older caterpillar in the fluff as I was starting to clean up. This gives you an idea of what it should grow to before pupating. He’s got a ways to go.

These little caterpillars form one of the primary food sources for Red-winged Blackbirds upon their arrival here in the spring. It seems like they’d need to eat a lot of them to get much nutrition, but evidently it works for them. A couple springs ago I got a photo of a female Red-wing poking at cattail heads. I thought at the time she was looking for nesting material, but having learned this, it seems apparent that she was actually searching for caterpillars. Who knew? Cotton candy indeed.

As for the book, I highly recommend it. It’s got great photos for an identification reference, and excellent information to complement them. The notable entomologist E.O. Wilson is quoted on the cover: “I wish I’d had Stephen Marshall’s book when I started out in entomology. Its countless photographs and notes bring alive the vast diversity of the insect world.” That’s like Roger Tory Peterson endorsing a bird reference book. There’s so much cool stuff in the book, lots to look at. The only downside: it weighs a tonne. Probably almost literally. At 730 pages and nearly two inches thick, a field guide it’s not. Still, it has the best collection of printed moth photos I’ve seen, plus so much other stuff, I ended up getting a copy myself (should be in the mail). It retails in store for $95, though generally cheaper online, but I found a copy on eBay for $33 plus shipping, so if you look around you should be able to get a good deal on it. Amazon has it on sale for $60. It’s also got a couple images of inside the book so you can take a peek before you buy.

Cattail thwacks revisited

Edit: This post was recently included in the 180th edition of Friday Ark, a weekly blog carnival focusing on animals of all sorts. You can check out the full edition at The Modulator.

One of the downsides to learning things yourself using the internet or reference books as your guide is that it’s pretty easy to mis-identify something based on poor photographs, incomplete descriptions or information, or just vague or ambiguous wording, particularly if you have a notion about what you’re expecting. In one of the posts I did mid-January, about fungus in the woods in winter, I mentioned a large, creamy, fuzzy mass I observed on the trunk of a tree that I identified as a slime mold. Well, Jennifer over at A Passion for Nature corrected me on this by (correctly) suggesting that it looked like a gypsy moth egg mass.

I went back yesterday to the same area and had another look at it. The particular one I photographed still looked and felt (to my frozen-numb hands) like a cattail thwack with no particular distinguishing characteristics (I didn’t want to try taking it apart because I don’t like to disturb). However, upon closer investigation, I started noticing more of these fuzzy blobs on nearby tree trunks, pretty much all within a few feet of the ground. Some of them had much more obvious visual characteristics that may have led me to the eggs conclusion if I’d seen them first. In the above and the first photo you can actually see the individual eggs wrapped up in all the little hairs that create the fuzzy mass (I think the first photo may actually be hatched eggs from last year? It’s hard to tell, but the dark spots are very pronounced). The hairs are made by the female moth as she’s laying her eggs, and are hypothesized to protect the eggs from potential rodent and avian predators by discouraging them from getting the hairs in their face and nostrils and irritating the skin.

Gypsy Moths aren’t native to North America (like a lot of common wildlife). Rather, they were brought over to Medford, Massachusetts in 1869 by French astronomer Leopold Trouvelot, who also had an interest in insects and was hoping to breed a sturdier, more productive silkworm. Well, like often happens, the moths escaped and it didn’t take them long to settle into the new landscape. They’re now found into eastern Canada as far north as Maine and the Maritimes, as far south as northern North Carolina, and currently west into mid-Wisconsin. When you consider the size of the insect in question, it’s a pretty good area to cover over that period.

The moth’s dispersal is also made more interesting by the fact that the female moth, the recognizable white Gypsy Moth, can’t fly. When she emerges from her pupa she’s full of eggs and way too heavy to get airborne. Male moths (which are brown) can fly, and will travel long distances to reach a female, which they detect using the broad, fluffy antennae that only males possess. These antennae are specially designed to pick up the pheromone molecules released by the female when she emerges. Near a couple of the egg masses I found pupa cases left from the female when she emerged. The cases also have hair tufts that presumably protect them the same way the hairs in the egg mass do.

Still, if the females aren’t moving, then the eggs are going to be laid near where the female emerges, which also doesn’t help much with dispersal. Instead, dispersal is carried out by the caterpillars (weird, eh? The only ones without wings). Caterpillars, during the course of their feeding, climb to the top of the tree and then spin a line of silk which they use to “balloon” on the wind over to the next tree. I can’t imagine this taking them very far, so it would be a very slow dispersal.

This photo (used with permission) is of a female caught in the act of laying an egg mass in late summer. She was found inside a porta-potty, so I can’t imagine the caterpillars would have much to eat when they hatch, but I gather Gypsy Moth females aren’t too particular about where they lay their eggs. The larvae will feed on up to 500 different species of trees, but particularly favour oak. Most of the egg masses I came across were on rough-barked tree species, primarily Black Cherry. Caterpillars hatch from their eggs in early spring, late April into early May. They feed on tree leaves and can be a severe pest in some areas where they completely denude trees of their foliage, particularly since a single egg mass can contain up to 500-1000 eggs. In late June to early July they begin to pupate, and emerge as adult moths after a couple of weeks. Females lay egg masses shortly after emerging, and adults will never eat. Adults die shortly after mating, and the species overwinters in the form of these egg masses.

It’s funny how once you know to look for something, it suddenly seems to jump out at you everywhere. Now that I’m aware of these and what they are, I’ll be keeping my eyes open for them on future walks.

The hundred-legged one

What is it about invertebrates that creeps people out so much? Cockroaches are the stereotype of unclean dwellings, and used dramatically to draw shivers from an audience, but really the insects probably have little to no interest in you personally. A spider crawling out of a drainpipe can prevent someone from stepping into a bathtub (no way was I climing in until it was taken outside or flushed down again), but the chances of it crawling on you, much less biting you, are pretty slim.

My personal insect-phobia, the one that will cause me to throw a garment into the air shrieking should I discover one hiding inside a seam, is earwigs. Creep. Me. Out. I’m not sure why, although perhaps it goes back to my childhood and having earwigs occasionally climb into clothing while it was drying on the line outside (I should note I was never bitten by one, but that didn’t reduce their creepiness). They particularly favoured the lining of bathing suits, for some reason. I’m also not terribly fond of silverfish, though that doesn’t have any childhood encounters tied to it. The rest of the groups I’m generally okay with, although spiders are better if they’re at a distance.

One guy I know revealed that he’s creeped out by leeches. Another guy said his was house centipedes, which was also my sister’s when I asked her. A couple days ago we had one of these show up in our bathroom sink (the photos in this post are of this obliging individual). I have to admit they’re fairly creepy crawlies, as creepy-crawlies go. Up to two inches long, with giant long legs that spread out in a large oval shape, long antennae and rear legs, and they can dash across a wall at lightning speed. They’ve never really bothered me, but perhaps that’s because I have all of my energy invested in earwigs.

Centipedes, unsurprisingly, get their name from their many legs (cent = hundred, pedes = feet). Millipedes also take their name from their many feet, but the “milli” means thousand. You can tell the difference between centipedes and millipedes because the former are usually flattened with just one pair of legs per body segment, while millipedes are rounded and have two pairs of legs per body segment. Millipedes have a defence mechanism of curling up into a spiral when threatened, while centipedes, which don’t have the same strong upperside, instead run away (and I challenge you to try catching one!).

There are a number of different species of centipedes in North America, but the house centipede (Scutigera coleoptrata) is the only one from the order Scutigeromorpha (the group is also called house centipedes; since the North American species is the only one on the continent, it can get away with using the group name as the species’ common name). It’s actually not even native to North America, but was instead originally from the Mediterranean and has since spread (hitching rides with humans or their cargo). It can now be found here as well as in Europe and Asia, and a few spots in Africa, Australia and New Zealand. In Japan, they’re reasonably popular and Wikipedia suggests it can often be found for sale in pet shops.

Millipedes are scavengers, eating detritus and dead material. Centipedes, including the house centipede, are predators, eating insects and arthropods commonly found in a household environment, such as spiders, ants, silverfish, cockroaches, termites and bedbugs, and as such could be considered beneficial bugs to have around. They kill their prey by injecting venom through small “fangs”, the same way spiders do. Although it is technically possible to be bitten by a house centipede, you would have to be intentionally or accidentally handling it, and even then it probably wouldn’t feel like much, as their fangs are too small to puncture most skin. The biggest house centipedes might be able to inflict a good bite if presented some soft skin, which would feel a bit like being stung by a bee, and would similarly subside after a few hours (also, a small number of people may be allergic to the centipede’s venom like some people are to bee stings).

Although they can be found almost anywhere in the house, they prefer damp locations, such as basements or bathrooms, or overwatered houseplants. Outside they can be encountered under rocks, in wood piles or in compost heaps. They’ll happily overwinter in your house, and are commonly seen in spring (or in mild spells mid-winter) when the weather begins to warm.

House centipedes start out with just four pairs of legs when they hatch, but go through a series of larval stages (“instars”) where they shed their previous exoskeleton (their hard outer shell – insects wear their skeleton on the outside and attach all their muscles to its inner surface, compared to vertebrate animals whose skeleton is inside with the muscles affixed to the outside). It may take them up to three years to reach full size, where they’ll have 15 pairs of legs (centipedes can have anywhere from 15 to 100+ pairs of legs, but the number of legs is always odd). Once full grown they can live up to seven years.

Adults have compound eyes, like many insects (though we tend to think of flies first), and so have excellent vision (also helpful, in addition to their speed, in evading capture). They’re the only group of centipedes to have this feature. They have three modified feeding appendages, “toothed” mandibles (visible in the above photo as a sort of beak-like shape under the face), a pair of maxillae, and a pair of leg-like palps (visible in the previous photo as . The mandibles “chew” the prey while the other two appendages manipulate it. The “fangs” are found on the first body segment, behind the head. I kind of think it looks like a grasshopper head, and if you couldn’t see the rest of the body you might almost believe it was related to this much less creepy crawlie group.

Mid-winter moth sighting

Speaking of hibernating insects, last night when I went to brush my teeth I discovered this little guy on the wall. The last time I saw a moth was probably back in November; generally speaking they’re not the sort of bug you expect to be out and about in mid-winter. So I was a little surprised to see it. I took some photos but otherwise left it alone. It was gone by the next morning.

I’m relatively new into moths as a group, but I’m fairly certain this one is Agonopterix pulvipennella. Moths are the sort of creatures where they’re either so obviously distinct it’s hard to mix them up with something (for example, a Luna Moth), or so similar to six other species that you really wonder just what criteria was being used in calling them unique. This one falls into the latter category. The key here is the dark spot on the wings, with a little white spot at the bottom, and a broad pale arch that crosses the shoulders and joins the two dark spots. But it takes a bit of scrutiny to identify, and it still looks like a bunch of other Agonopterix species.

A. pulvipennella, it turns out, doesn’t die with the cold weather, like many insects do, but rather overwinters as an adult, and then comes out to breed in the spring. Like the ladybugs and wasps, it will often choose cracks in the walls of your house to crawl into to settle down for the winter. When the weather warms up a little, they can end up in your house. What was funny about this one is that yesterday it was rather nippy out (not helped by the gale-force winds), so I guess it’d come out the day before (when it was nice and mild) and had been hanging around, unseen.

It seems to be a relatively common and widespread species, found throughout much of northeastern North America. The larvae feed on the leaves of goldenrod and nettle during the summer. They pupate in late summer, and adults emerge starting in August. Although the moths are about throughout the fall and into the spring, they’re apparently most commonly seen in the spring, which seems sort of funny to me. Perhaps because, to a moth, UV wavelengths mimic the pheromones of a female, they’re more likely to be attracted to lights, where we can see them, in the spring when looking for a mate?

A visit from the queen

The temperature today was an incredibly balmy 8 degrees Celsius. This was a one-off, however, because a cold front is supposed to roll in tonight and tomorrow is forecasted to be -10 oC (I shouldn’t complain; today in the Canadian prairies it was -50. Before windchill). Still, the warm weather was nice. I wasn’t the only one to think so. This afternoon I found a wasp crawling, somewhat sluggishly, along the windowsill in the den.

In my very first post I talked about the appearance of ladybugs mid-winter. Wasps are very similar visitors. They crawl in to cracks in the walls of the house in the fall when looking for hibernation spots to spend the winter. Normally they would only come out when the warmer spring weather finally arrives, but warm spells can cause a few to come out prematurely. Those that chose to hibernate in your house will quite often go the “wrong” way, toward the warmer temperatures inside, and end up crawling along your floor or windowsill.

Wasps are like honeybees, in that most species spend the majority of their year living in colonies. There’s a queen who “rules” the colony, although her primary job is simply laying eggs. There are sterile worker wasps, who spend their time collecting food for the young grubs and the queen (and themselves), repairing and defending the nest. And there are fertile male wasps, whose only job is to mate with new queens.

In the spring, a new queen, who mated with a male before going into hibernation in the fall and stored the sperm inside her, will pick a site for the nest and start a new colony. Depending on the species, she may start it alone, or with a few of her sisters who overwintered with her. She lays fertilized eggs, which develop into sterile female workers. She’ll care for the first couple of broods herself, but once there are enough workers to tend to the eggs and larvae properly, she concentrates on just laying more eggs. Once the sperm runs out, in mid- to late summer, the unfertilized eggs grow into fertile males and new fertile queens, who go out and mate, and start the cycle again. The wasps that turn up in your house in the middle of winter are all young mated females who have gone into hibernation till the spring. All the other groups – the original queen, the sterile workers and the males – died once the weather turned cold (if not before).

These mated females are stingless. The initial reaction upon seeing a wasp, particularly if you have kids or pets, is to worry about someone getting stung. However, the stinger in wasps and bees is a modified ovipositor (the body part used to lay eggs). Males don’t have an ovipositor to begin with, and mated females need theirs to lay their eggs come spring. Only the sterile worker females have the ability to sting. I suppose she could give you a good chomp with those powerful jaws (look at the size of them in that first photo!), but it’s unlikely to feel like more than a pinch. Paper wasps use their jaws to strip bits of wood from logs or dead trees, which they then mix with saliva to create the “paper” used in building their grey papery nests. If you spend a lot of time on your deck in the summer, you might catch one collecting wood from the deck or siding.

Wasps are generally predatory, preying on other insects, although they can sometimes be seen feeding on the nectar of flowers. The particular composition of their diet depends on the species. They’re useful to have around your yard because they’ll take care of many other undesirable bugs in your garden or around your home. As long as you don’t actively disturb their nest, or pester an individual (intentionally or not), they’re generally fairly docile, willing to let you do your thing while they do theirs. If it’s a mild day when you come across a wasp in your house, let her crawl onto a piece of paper and then transport her outside, where she can find herself a new hibernation spot, and she’ll take care of your garden for you come spring.