cocoon

Tussock moth cocoon

Periodically I pause to check the three great, old maples in our front yard for interesting goings-on. I’m not looking for anything particular. An interesting bug, perhaps. Some fungus maybe. Whatever’s happening on the trunks at the time. Sometimes there’s nothing at all that catches my eye. But about a month ago I spotted these. There were three of them, two on the biggest maple, and one on the third. I’ve continued to check on them, from time to time, as I do my maple trunk surveys; they’re still there, and I expect will be for the winter.

It was pretty obvious to me from the outset what they were: those hairy, oval masses couldn’t be anything but moth cocoons. But what was the hard foamy mass on the outside? I had a suspicion, but I took some photos and came inside to confirm.

Sure enough, the answer was on page 71 of the fabulous Tracks & Sign of Insects. The cocoon belonged to a tussock moth. This group of species lays their eggs on the outsides of their cocoons – because the females are flightless, and so don’t travel far.

That answered what. But what about who?

I noticed as I was examining them that inside the hairy cocoons were the hard shells of pupal cases. I couldn’t really tell if there was still a moth in the case or not, so I reluctantly peeled one off the tree to see (I don’t like to disturb things usually, if I can help it). As I flipped it over, I noticed two things. The first was that the case was empty. I hadn’t yet gone in to look up the book at the point that I was examining the cocoon, but if, as I suspected, the white mass was eggs, then it wasn’t a great surprise that the case was empty.

But the other thing that was obvious was the three white spots on the back of the case, remnants of the outfit the individual wore as a caterpillar. This quickly answered the who: this was the cocoon, and egg mass, of a White-marked Tussock Moth (Orgyia leucostigma). Caterpillars of this species are striped lengthwise with yellow and black, bearing three long, dark tufts at the front and rear, and four short, thick white tufts along the back. Very distinctive!

The species overwinters at the egg stage (which makes sense if they were laying them in the fall). Caterpillars are about as generalist as they get. Caterpillars of Eastern North America lists as possible host plants “apple, birch, black locust, cherry, elm, hackberry, hickory, oak, rose, willow…fir, hemlock, larch, spruce and other conifers.” They’re fairly common, so you might well find a cocoon or two if you try checking out some old, ridgy trees.

Here’re a few photos of the species, including one of a female in the act of laying eggs (how cool!).

White-marked Tussock Moth Caterpillar by cotinis on Flickr (CC licenced)

White-marked Tussock Moth, view from behind - Moth is looking "furry"! — White-marked Tussock Moth, view from behind by Vicki's Nature on Flickr (CC licensed)

8316 - Orgyia leucostigma - White-marked Tussock Moth — Adult male White-marked Tussock Moth

Hatching a pupa

Two weeks ago, the same weekend Dan walked back with me to show me the jewelwings, he pointed out what he thought was a chrysalis that he’d spotted dangling from the branch of a shrub alongside the path. (This was the primary purpose of the expedition; the jewelwings were a nice addition.) When I stooped down for a closer look, it turned out not to be a chrysalis at all, but actually the pupa of a moth that had slipped out of its silken cocoon. (Butterflies, when they pupate, form hard-shelled cases without any additional protection, while moths usually form soft-shelled pupae that they encase in a cocoon spun with silk fibres, sometimes incorporating other material such as leaves.) The fibres of the cocoon were still affixed to the branch, but now the pupa dangled delicately from one end. From rain, perhaps, or other weather effects?

I took a few photos of it in situ, and then (at Dan’s suggestion) carefully broke the branch off to bring it back to the house to try to rear it and see what was inside. I placed the twig into a large, clear mason jar, crumpling up a tissue and placing it underneath one end so that the pupa would be elevated from the floor of the jar, aware that the moth would need room to be able to stretch its wings out as they dried. I covered the top with cling wrap to keep the moth inside until I found it, poking half a dozen holes into it with the tip of a pen to allow air circulation. And then I put it on the kitchen counter and waited.

Four days later when I came home from work, Dan pointed out a moth inside the jar. But it wasn’t the moth I was expecting to be inside the jar. Not that I had any idea, really, what species was inside the cocoon, but I did know that as the pupa was about 15mm (3/4″), the moth inside it would also need to be at least that big. The moth fluttering about the jar now, scurrying over the cling wrap and around the glass walls, was just a little micro, less than a centimeter (1/2″) long. I jarred it and placed in the fridge to cool, with the intention of slowing it enough that I might be able to manage a decent photo to identify it. I eventually got one through the clear plastic of the container, but it was sufficient to pick out a probable ID: Olethreutes albiciliana, a member of the family Tortricidae for which there is several records but no detailed life history information on the web. The records I’ve found have been for Alberta, Ontario, Indiana, Massachusetts and Vermont, suggesting it’s primarily a northeastern species perhaps extending west through the Boreal. I don’t recognize the plant it was attached to, but the substrate the caterpillar pupates on isn’t necessarily the same one it was feeding on.

A closer look at the plant revealed this tiny pupal case affixed to the twig at the base of some leaves. It looks a bit like a mantis or some other bug, but the long hooked “arms” are just bits of the pupa that split along thinner creases in the shell when the moth forced its way out, probably where the pupa traced the antennae (if you look closely at the top photo you might see that the pupa clearly shows an abdomen, two sings wrapped around the front, and the antennae folded down against the body in front of the wings. It even sort of shows the eyes, though they’re harder to see). It’s funny that I hadn’t even noticed this one when I broke the twig off and brought it inside.

It was a longer wait for the original pupa to “hatch”. Finally, when I came home from work yesterday afternoon, two weeks after collecting it, the top of the shell had been neatly popped off and lay on the floor of the jar.

And running around the mouth of the jar, under the cling wrap trying to find a way out, was the adult that had emerged from it. But it wasn’t a moth at all. It was a wasp!

I chilled this guy, too, and then took a couple of photos which I posted to BugGuide. The long, narrow body and antennae identify the wasp as a member of the family Ichneumonidae, a group of wasps that parasitize the larvae of other insects, primarily lepidoptera (moths and butterflies) and beetles. The expert on BugGuide placed it in the subfamily Ichneumoninae, and I browsed through the BugGuide catalogue till I found a possible match: Ichneumon annulatorius, based on thorax and leg markings and lack of white on the antennae. This species also seems to be a northeastern species, based on the locations of specimens submitted to BugGuide for ID.

This PDF had some useful information about the group, including the species I. annulatorius. The wasps emerge and mate during the summer and fall. The females then spend the winter hidden under loose bark or sometimes moss on trees or logs. In the spring, they begin searching for a suitable lepidopteran host, either caterpillars or newly-formed pupae, and lay their eggs, fertilized using the sperm they’d stored over the winter. The wasp larva develops in the pupa and emerges a few weeks later to start the cycle again.

This individual is a male, as it lacks a long, thin ovipositor at the tip of its abdomen. After I’d got my couple of photos I let him go so he could find himself a female. Interestingly, though, the paper notes, “Specimens may also be held for months at room temperature by supplying ample water and nutrients in the form of a 50/50 honey/water mixture.” If you think of the amount of time between when a female would have emerged from her host pupa in the summer, to when she lays her eggs the following spring, they actually have a reasonably long lifespan, for an insect. Although I don’t think the males sting, lacking the ovipositor (which is the organ that stingers are modified from), it’s hard to think they’d make very good pets.

Not eating much

I woke up this morning to a very white, white world. Yesterday we’d gotten a bit of snow overnight, but not a large accumulation, and because of warm mid-day temperatures it had already started to melt. It seems that once things cooled overnight we had some more snow push in. The trees are covered in a thick layer, and it’s still falling, making the forest on the other side of the field slightly hazy. These two days represent the first real accumulation of snow we’ve had since the Christmas storms. That’s two months of nothing but light sprinklings. Meanwhile, our friends south of the border seem to have been hit by storm after storm this winter. Sorry guys. Someone up here must’ve been offered Three Wishes.

Although we hadn’t gotten to the point of seeing bare ground prior to yesterday’s snow, we had experienced a fair bit of melt, exposing some of the more well-traveled or sheltered places. We’d had a number of moderately mild days, with sustained temperatures slightly above freezing. Ducking under one of the spruces by the garden on the return from a hike one day I’d noticed an iris that seemed to have escaped the garden. It was valiantly trying to push its way up through the remains of last year’s plant and the accumulation of dead needles on the ground. It’s funny how irises and lilies seem so gullible.

Wondering if there might be any other plants tricked into sprouting by the warmer weather I did a tour of the bare areas surrounding the house. I didn’t see any other green bits, but I did discover a small plastic bag by one corner of the foundation. In it were a dozen bulbs that I’d planted at the last house and then dug up and brought with me to the new one. They’d been set there when we moved in, and the garden’s vegetation quickly grew over so I’d completely forgot about them. I figured they’d all be dead, having spent the winter above ground out in the freezing cold, but had a peek in the bag anyway. Lo and behold, one was sprouting!

I brought the bag inside with the intention of planting the one bulb in a pot. I think it’s a scilla, although I’ll have to wait for it to grow a bit bigger to be sure. I put the bag on the counter while I went and rummaged for a pot and soil. When I returned with the necessary implements I opened the bag and started flipping through the other bulbs to check for any other life. The second one I flipped over had this guy hiding underneath! The bag hadn’t been sealed; when I bundled up the bulbs a couple of them had mostly-dead stems still attached that I’d just closed the bag around. It appears this guy snuck in through the small opening and had cozied up there for the winter.

It’s a Hemipteran, a True Bug. My first thought was that it was a leaf-footed bug like we see so many of in the house in the winter, but if it was it would’ve had to have been a nymph because it was too small for an adult. It also lacked leafy leg flanges. My next thought was that it was an assassin bug of some sort, especially given that long, strong proboscis, which assassin bugs use for piercing their prey. So I flipped open my favouritest Insect identification guide, the Kaufman guide to insects, which always has all the answers. Well, almost always. And sometimes only half the answer. But very rarely do I open it and not find something helpful. This time, it had the whole answer, and practically on the first Hemipteran page I flipped to.

This guy’s a Damsel Bug in the genus Nabis. There are nine species in this genus in North America, nearly all found in the northeast. As I had suspected by the strong proboscis, they are predatory, feeding on other soft-bodied insects. They can be told from assassin bugs by their tapered shoulders and thickened forelegs. They appear to favour fields and gardens, and overwinter as adults.

Naturally, when I found the bug I didn’t have my camera. I dashed upstairs, switched out the lenses for the Macro, and hurried down to try to get a photo. When I got back, I couldn’t relocate him immediately. As I searched I discovered a few other critters crawling around in the dirty bulbs. The first one I spotted was this beetle, scurrying quickly out from under his disturbed hiding spot in an effort to find new cover. I haven’t a clue what it is, beyond being a beetle. It was tiny, less than half a centimetre (<1/4"), and a very generic, unmarked brown. I would hazard a guess at a type of leaf beetle, but, being a beetle and therefore among the most diverse group of organisms on the planet, it would be a very hazardous guess. My friend Ted over at Beetles in the Bush would undoubtedly know.

Speaking of Ted and beetles, this would be a great opportunity to mention that the brand-spankin’-new blog carnival dedicated exclusively to beetles, An Inordinate Fondness, just enjoyed its inaugural edition over at the carnival’s home page. Ted put a lot of time, effort and care, and perhaps even some sweat and tears, into bringing the project to fruition, so I highly encourage anyone who loves beetles, or likes them, or is even just the tiniest smidgeon interested in them, to pop over and check it out.

Then I found this arachnid. Clearly an arachnid because it’s got eight legs, it’s also clearly a harvestman because it’s got only one body segment. Harvestmen are related to but not actually spiders in the true sense. We’re mostly familiar with harvestmen as the creepy Daddy-long-legs with their spindly Tim-Burtonesque long legs. There are, however, some with long legs, some with short legs, and some with no legs at all! Okay, so not really on that last bit, but there’s definitely more diversity to harvestmen than you might initially think. There are some 6400+ species worldwide. The unifying feature is the single-segmented body. The actual identity of this individual will probably remain a mystery, though, since I lack the expertise to know what to look for, and there’s a good chance that the ID depends on some bit of microscopic anatomy, as is often the case with invertebrates.

Speaking of arachnids, I also spotted this tiny little spider scurrying across the folds of the bag. I think this is probably a dwarf spider, family Erigoninae, a group of fairly common but particularly tiny and therefore usually overlooked spiders. Genus is less certain, but possibly Ceraticelus. This one is a male, as you can tell by the two swollen appendages in front of its head (like big mitts, they’re primarily used in transferring packets of spermatophores to the female’s body, so females don’t have them).

And finally, an inanimate addition to the collection. I don’t know cocoons very well, beyond that anything built with silk is probably a moth. The only hard-shelled cocoon like this that I’ve seen and had ID’d before were the sawfly cocoons I found under a pine tree last winter. Could this be a dipteran cocoon, then? Something else?

I put the bag of bulbs, critters and all, down in the basement when I was done. Now that I’d woken them all up and disturbed them, putting them back outside would possibly mean death. Also, I wanted to see if, with sustained warmer temperatures, any of the other bulbs might try to sprout. I wasn’t concerned if any of the little critters happened to escape and disappear into the house. As my dad used to say, when we were kids and pointed out a bug getting a bit too close for comfort, “that’s okay, he won’t eat much.”

Homes for the winter

Here’s some of those photos I’ve had sitting around for a while, waiting for an opportunity to post about them. This first one I’ve had since January! I came across this interesting structure while out with Blackburnian during the Colour-coding Chickadees walk. I had no idea what it was at the time. It was already open when I came across it, and there was nothing in it. It resembled a cocoon, but I didn’t really know. Lots else to post about, so I never got around to looking it up.

Then in mid-February, Jennifer over at A Passion for Nature posted a cocoon she’d been seeing on some of her walks, and a couple days later she posted a follow-up about the cocoon’s occupant. Turns out, it’s the cocoon of a Cecropia Moth, one of the North American silk moths, a group of beautiful, giant moths whose caterpillars spin “silk” which they use to create their cocoons. Jennifer directs her readers to a rather amazing site that documents the life cycle of the moth from egg to adult (and now I’ll direct you there, too!). The site indicates that the moths overwinter as pupae, so the fact that this cocoon is split open likely suggests that it’s either last year’s case, or somebody/thing got to it before I did this winter.

This second one is also a moth, and I’ve also had it on hand since January. I knew right away what this one was when I saw it, from having browsed through the Moth Photographers Group website while identifying a few moths last fall. Of course, I couldn’t remember exactly which it was, just that I’d seen it on the pages, so I had to go back and scan through their many (very useful) pages all over again.

The case, which superficially reminds me of those made by caddisfly larvae, is made by a moth belonging to the group of “bagworm moths”. This one’s probably Psyche casta; the different species have different case styles, but I would assume some of them to be subtle. Like the caddisfly, the moth larvae tote this bundle of sticks around with them until it’s time to pupate, at which time they affix it to a solid surface for the winter. I found three of these all sitting in the window frames of my parents’ house. Two were between the panes of glass, but this third one was on the interior frame, which made it easier to photograph, but also meant it was exposed to spiderwebs, dust, pet hair, etc.

Wikipedia indicates that many bagworm moth females have vestigial wings, and sometimes never leave their cases, mating with males even while still inside. They die after mating, either having laid the eggs inside the case, or without having laid the eggs (so the larvae mature and emerge from the female’s body). The eggs are very hardy, and a bird that finds the case and eats it will pass the eggs through its digestive system intact, aiding in the spread of “new blood” from one area to another.

And this final case isn’t a moth or butterfly cocoon, but instead was created by a Praying Mantis. They started appearing late last fall, and I think I found five in total, four of them laid on the research station’s exterior walls. I didn’t know what this was at first, either, but I think one of the volunteers at the station pointed it out and identified it for me. They were still there, all of them, when I was back for the start of the spring season. When they were first laid they were a little gooey to touch; now they’re all quite hard.

I read somewhere that they’re always laid on the south side of the object they’re affixed to, which is actually true of the four on the station building. The one pictured here, however, found at the base of a metal signpost, was on the north side. I guess that one didn’t get the memo. Mantids are fairly common at the spit, which is pretty neat, since I never saw many growing up. Despite their slightly startling, ferocious appearance, they’re pretty tame to pick up and handle, not inclined to bite, which makes them great for showing to kids. Just like hatching a cocoon, you can bring these cases inside and set them up in a terrarium to hatch – or, if you don’t want to risk damaging the wild ones, you could order your own Praying Mantis Encounter from Discovery Channel’s store, and treat the kids (or yourself) to a neat experience watching them grow. Only available to the US, unfortunately, or I’d order one! :)