invertebrates

Common Buckeye

A couple of days ago Dan brought me a surprise: he’d caught a Common Buckeye out in our fields. Buckeyes don’t normally occur here. They’re a southern species that only occasionally strays far enough north to be recorded in eastern Ontario, and nearly all the records are from the southern edge of the province. My mom spotted one last year at her place just fifteen minutes north of the St. Lawrence. It was the first one she’d ever seen. The one Dan brought me was the first one I’d ever encountered, too (perhaps surprisingly, given the time I’ve spent working and traveling in the US). But interestingly, this was actually the second one Dan’s found here on our property this summer (I was away when he found the first one).

The foodplants for this species, such as snapdragons and toadflax, do actually occur in our area. However, like Red Admirals, the adults of this species are not cold-hardy and can’t survive the winters of the northern half of the continent. Instead, the butterflies seen in these areas are migrants that move north from the warmer southern regions. It was a really big spring for Red Admirals this year, possibly because the mild winter we had allowed more to survive than ordinarily do, and perhaps survive farther north than they normally can. I would guess this same weather probably benefitted the buckeyes, too.

It’s been a great summer for butterflies all ’round. In late May and June we were seeing a lot of Giant Swallowtails; they were more common even than our regular Tigers. I posted about Giants before, when we got one last summer. They also don’t normally occur here but will occasionally irrupt north. I’m not sure if they’re also affected by winter temperatures, or if the numbers we had this year were the result of some other factor.

Silverfish

The teabags I use for everyday use are of the two-cup sort. I sort of felt like I was wasting half a teabag when tossing them into the compost after just one use, so for a while I’d started saving them on a plastic lid for a second use later in the day (and since I usually have multiple cups in a day, they didn’t normally sit long). This stopped last week when, upon lifting the saved teabags, I discovered a silverfish underneath.

I very nearly dumped the silverfish along with the teabags, but changed my mind in time. This isn’t the first silverfish I’ve ever seen and it definitely won’t be the last, but it was the first one that was on a conveniently portable surface that I could set up my camera over. And it was being remarkably cooperative, sitting still while I moved the plastic lid around. It might be the best opportunity I’d get for a silverfish photo, at least foreseeably.

There are apparently 18 species of silverfish in North America, organized into three families. Of these, one species (in its own family) is found exclusively in carpenter ant nests in forests of northern California and Oregon. Another four species (in the second family) are restricted primarily to caves, termite nests and other subterranean habitats in the southeastern US. The rest (in the third family) are widespread and found in many habitats. Two are found around the world and are common inhabitants in our homes: the Common Silverfish (Lepisma saccharina) and the Firebrat (Thermobia domestica). The former is typically resident of our damp areas, most usually the bathroom, while the latter sticks close to heat sources and is normally found near furnaces, hot water heaters, insulated ductwork, etc. This one is a Common Silverfish. I’ve never seen a Firebrat.

I have to admit I’ve always been fascinated by silverfish, in a slightly creeped-out way. Their fluidity of movement is sort of unreal. Till now I’d only ever observed them in washrooms, and I was perfectly happy for them to stay there. However, they’re not harmful in any way, really. They don’t bite, and don’t spread disease. They’re vegetarians, with a sweet tooth: their scientific name, saccharina, refers to their preference for sugars and starches. They’ll take these where they can find them, be it glue in wallpaper or book bindings, starches in natural fibres (both cloth and paper), or food scraps or other biological material. (Wikipedia lists dandruff, even.) But if necessary, they can go without food or water for weeks.

An individual silverfish can live as long as two to eight years. Think about that. If you moved in the last few years, there might be silverfish in your house that have lived there longer than you have. Fortunately, they’re not that prolific; a female may lay fewer than 100 eggs in her lifetime. And a healthy household population of earwigs, spiders and house centipedes will also help keep their numbers down.

I’m sort of tempted to paint a dot on the back of the next one I find, except they continue to moult even as adults, so it might shed the dot before the next time I see it and I’d never know. I guess I’ll just stick to watching from a distance.

Early tent cat nests

A week ago when I was out with Raven a glint of white in one of the black cherry trees in our back fields caught my eye. Wondering if it could possibly be a tent caterpillar nest so early in the season, I checked it out. Sure enough, it was. This feels very early to me, but I admit I’ve never caught the nest at such an early stage before, barely started. Normally I check in when it’s already the size of my fist or thereabouts. I start noticing them (without having to consciously search) in early May usually. Was it just that I was paying attention this year?

Part of the reason I was watching was because of the warm spell we had in March, of course. I worried that it would not only accelerate the budding-out of the trees and shrubs, but also the growth and emergence of early-spring species. I did, in fact, have an Arched Hooktip (a moth) show up at my light one night at the end of that week; ordinarily the species first shows up in mid-May, so it was nearly two months early. It didn’t seem a stretch to think it might have prompted the tent cats out prematurely, too.

When I investigated more closely I discovered all the little caterpillars in this particular nest were dead; blackened and unmoving. We’d had several nights in a row of freezing or just-below temperatures, including one hard night of several degrees below. I wondered if that had killed them. Tent cats use their tents to help thermoregulate, and I would assume that, since we still get frosts potentially as late as mid- to late May most years, it also serves as protection against frost. But the little nest of these cats was still so small, perhaps the size of a plum. Maybe it didn’t provide enough protection.

When I did my usual late-winter walkabout searching for tent caterpillar eggs I only found a few clusters, all on the same tree. The other trees that have had them in most past years didn’t have any, so I was already starting to wonder if it’d be a year of low abundance for the species. This freeze won’t have helped, if it’s killed all the caterpillars from this egg cluster. I couldn’t really tell if all the eggs had hatched or only some of them. I’ll hope some hadn’t hatched yet and might go on to build a new nest.

In another field I found a second nest. This one was larger and the caterpillars on it obviously older – and, happily, still alive. They were clustered together sunning themselves on the surface of the nest, which they’ll do on cooler days. This nest was closer in size to an orange, so I wondered if the extra layers of silk had helped protect the caterpillars against the cold.

They’d already started making their silken trails up the branch from the nest to their feeding location. This is one of the reasons tent caterpillars appeal to me so; there’s so many neat aspects to their biology that are fascinating to look for. They leave this trail as they walk so they know where the nest is when it’s time to return. The nest is their protection from both the elements and predators, so you can understand the desire for a lifeline like this.

These were the buds the line was leading up to, though. The whole tree was like this. There can’t honestly be enough plant material there to sustain them yet, can there? I guess they’ve got little mouths and wouldn’t eat very much, so maybe there would be. The nest was full of frass (see the little brown dots in the photo with the sunning cats), so they were obviously eating something, and it was orangey-brown like the bud sheathes here.

I’ll be keeping an eye on these guys over the next little bit to see how they do – not that there’s much I can (or would) do if the weather goes cold again. But I like to keep tabs on my local families of wildlife, and tent cats are such easy ones to monitor…

Cats / tracks

I’ve been waiting for a really nice, sunny, mild day to head out with my cordless drill to clean out our nestboxes, and the weather conditions were perfect for it this afternoon. I took photos and will follow up on that on probably Wednesday.

While I was out there, though, I saw a number of other critters enjoying the sunshine like I was. I spotted a few fuzzy caterpillars, mostly Woolly Bears like the above. They emerge so early, I don’t actually know if they spend any time eating before they pupate. There wouldn’t be a whole lot to eat yet. Although, I did spend some time raking out our garden, and the first shoots of daffodils and croci are coming up, as is the rhubarb. And quite a number of plants stay evergreen under the snow. So maybe there would be enough.

On the way back to the house I came across this guy, who I initially mistook from a distance to be another Woolly Bear, but who turned out, upon closer inspection, to be a Giant Leopard Moth caterpillar. I still get inordinately pleased whenever I discover one of these guys, even though they’re not uncommon here. We didn’t have them where I grew up (or if we did, I never noticed them); it wasn’t till I moved east that I started seeing them. So I still get that thrill of somethingcool! when I find one.

As I was walking back from the last nestbox I noticed a robin off some distance away in the forest, making a lot of noise in the leaf litter. I’d brought my binoculars with me (something I don’t always do, since I do most of my birding by ear these days and it’s one less thing to carry around) so I was able to watch him closely. After a moment or two he picked something up, dark and thick and C-shaped, carried it a short distance, then plunked it down in the leaf litter. I’m fairly certain it was a dark fuzzy caterpillar like one of the two above. I think he might have been trying to de-bristle it prior to eating it.

I made a brief detour out to the rail trail and walked down to the creek, and discovered these tracks out there. What first caught my eye was the size of them. Certainly much bigger than any deer I’d seen around here. They’re cloven like deer and domesticated ungulates (except horses/donkeys), but there was really only one animal I thought could make something that large, at least that I would reasonably expect might be found walking down the rail trail. Which is a moose, of course.

Having seen a moose in our back fields last fall, this wasn’t quite the stretch that I might have otherwise thought it. It’s possible he’s hung around the area, in one of the swamps nearby, keeping out of sight. I took a few photos and double-checked my tracks guide when I got back. They seem to be potentially confusable with domestic cows, with the main distinguishing feature being the front of the track – the hooves are pointed in moose, but rounded in cows.

You can’t see it as well in the first photo, but you can tell in the second that the front of the tracks are pointed. It was pretty clear in person, too, that the paired hooves were long and tapering at the front. They were relatively fresh… I didn’t notice them on my way out, only on my way back, though that’s not to say that they weren’t there and I just missed them on the way out. I tried following them to see where they went, but they seem to curve out from the fenceline and then back into the fenceline. I can only presume he jumped the fence, then got spooked after walking only a short distance down the trail and jumped back. And yes, moose, like all deer, can jump:

Who Knew? - Moose Jumping a Fence Photo by Bruce Barrett (nordicshutter) on Flickr; CC-licensed (the only such photo I found of a moose jumping, though there are others that are not CC)

A potato surprise

A few weeks ago I was preparing dinner and pulled out and peeled a few potatoes for whatever meal I was making. Three were just fine, but when I cut open the fourth it was dark and decayed all down the centre. I was surprised; there’d been a small blemish at one end, but there are often small blemishes and I just cut them off and use the rest of the potato as normal. But this one was hollowed out.

As I was contemplating whether it was worth cutting out the decayed bits and using whatever was left, or if the smell/taste of the decay might have permeated the whole potato, I saw what I thought was a bit of movement. Tiny, thin slivers of silvery-white, no wider than two or three hairs. I thought they were hairs at first, until they started crawling.

So I did what anyone who found their grocery-store potato infested with tiny silver worms would do: I put the potato slices in a bowl, covered the top with cling wrap, poked a couple of holes in it, and brought it up to my study for observation.

I wasn’t sure what to expect. I was kind of thinking they might be fruit flies, because that seemed the most logical choice for an insect that’s snuck home in fresh produce. But I figured if I just exercised a bit of patience, hopefully I would see. If they were in fact fruit flies, I’d have less than two weeks to wait – which is how long it takes a fruit fly to go from egg to adult stage.

I kept checking on it. After a couple of days I realized the potato was starting to dry out, so I started spritzing it once a day with water to try to keep it moist (not too much; I didn’t want them to drown). It would’ve been better if I hadn’t peeled the potato, but at the time I was peeling it I didn’t realize it held a secret inside.

Five days later, when I peered closely I noticed what seemed like a lot of tiny pearl-white seeds congregated in one spot within the decay. This was exciting! I figured they were nymphs, or the next life stage of whatever it was that the potato was growing. I got my camera and macro lens and got the closest shot I could of them.

This is the image, cropped to 100% – as close as I could get. I’ve been having some trouble with my camera card reader on my computer – it works, but takes some patient fiddling with – so I didn’t check them out closely right away. On the back of the camera, though, they kind of looked like tiny beetles, like maybe a nymph stage. I knew that beetles have a worm-like grub stage, and I’d already observed worm-like grubs, so that’s what I figured they were. Beetles. Just needed to wait till they grew into adults to find out what type.

I waited some more. Another few days went by. Finally, one afternoon I peered in to the bowl and there it was! The adult!

It wasn’t a beetle.

It was, in fact, a gnat of some sort. (Beetles, I learned upon further research, don’t have a nymph stage; their larval instars all look roughly the same. Ditto for gnats. More on this later.) Unfortunately, it accidentally got squished before I could get a photo, and only two adults ever emerged from the potato halves; I wondered if I hadn’t been keeping it damp enough in the decaying sections. So I don’t have a photo and can’t definitively say what it was. But it looked something like this:

This happens to be a fungus gnat that drowned itself in my tea a couple of years ago.

My beloved Kaufman Guide to Insects doesn’t have much on gnats, so I turned to Google, which knows everything. Fungus gnats can be a real nuisance problem with indoor houseplants, and nearly everything Google turned up pertained to using a raw potato slice, placed on the soil surface, to draw the fungus gnats out of hiding so they can be removed. From this I deduced that they must actually use potatoes as hosts, at least occasionally.

I had to dig a little deeper but I did finally find a page in amongst the household remedy hits that confirmed this. This University of Florida information page said:

Most species of darkwinged fungus gnats (Sciaridae) feed on fungi and decaying organic matter and are not considered economic problems. A few species, however, attack healthy tissue of such economic plants as potatoes, wheat, red clover, alfalfa, cultivated mushrooms, pine seedlings, and various ornamentals, including tulip bulbs, ferns, begonias, coleus, geraniums, cacti, young orchids, areca palm, and dracaenas.

That’s quite the list! But heading it up is potatoes, which was the one I was interested in at the moment. Figure 2 on the page is actually of the worm-like larvae in a decaying potato.

Anyway, back to this photo:

I thought it was a larval stage of the beetle-no-actually-gnat. Until I double-checked the life cycles of beetles and gnats, and neither turned up any reference to a tiny, globular larval stage. That’s weird, I thought. But I image-googled “fungus gnat larva” to be sure. It was all photos of adults or the thin, silvery worms… except there were a couple that were round, slightly-haired critters.

Following the first image brought me to this bug-control page, which was a sales page for a live shipment of the invertebrate Hypoaspis miles. They’re predatory mites, and one of their primary prey items is – you guessed it – fungus gnat larvae. It says they are a soil mite, native, and fairly versatile in terms of habitat/substrate. Was that what I had? Predatory mites that ate all my fungus gnat larvae which was why I only got two adult gnats? Unfortunately, I don’t think the photos I took are of good enough quality to know for sure, but that’s the way I’m leaning.

So even though I only got two adults and ended up with more mysteries than answers, I’m considering the potato experiment a success.