Merry moths of May

Polyphemus Moth

I haven’t posted anything about moths in a little while. Part of this is that there haven’t been many moths to post about. The weather over the last month has been unseasonably cool and rainy. The few nice days we’ve had generally haven’t corresponded with times where I could get out to set up the lights, and the nights I would have had the opportunity to set up, were cold and not good for moths (there was actually frost a few nights ago!).

However, I have done a little bit of mothing. For instance, I went out last night, down to the research station where I set up the trap to leave running overnight since I was going to be in this morning anyway. And since I was down there, I thought I’d stick around for an hour or so and see what I could get in to a sheet. The answer: not too much. I got hundreds of mosquitoes and midges, but moths were scarce. On the other hand, the dozen or so I did get were more than I’d got to the sheet on previous visits to the station. So I shouldn’t complain too much.

The highlight was the above Polyphemus Moth. This giant moth, about the size of my open palm, is a relatively common member of the silk moth family. They have huge, globular, bright green caterpillars that spin large silken cocoons on tree branches (which I wrote about in an earlier post). I’m not sure if this is the actual resident from that cocoon, but I discovered him rustling in the grass not too far from my light, which in turn was not too far from where the cocoon was. One of the things having him up close like that allowed me to notice was that the centres to the spots on the wings are actually transparent. They look like holes in the wings, but are actually clear membrane. This is apparently a feature shared by many of the silk moths. It sounded like it was squeaking while I had it in the net I caught it in, but I’m not certain about that – I found reference to a few types of moths squeaking, but not silk moths.

Black-rimmed Prominent

This is a Black-rimmed Prominent. I discovered it, perched at the edge of the sheet not far from the trap, when I arrived in the morning and went to shut the trap light off and take the sheet down. The prominents are a striking group, many sleekly coloured like this. This particular species is found coast to coast in North America. The caterpillars feed primarily on the poplar family, which is not in short supply at the station.

One-eyed Sphinx

A couple weeks ago I had a warmish night while at my parents’ and set up a couple of traps to see what I could draw in. It was a pretty good night, with some 30 species of moths. As I was closing up shop for the night, taking down all but the trap, I discovered this guy hanging from the clothesline where I had one of the blacklighted sheets suspended. It’s a One-eyed Sphinx, so named for the single eyespot on each hindwing. The sphinx moths are a pretty neat bunch. Along with the silk moths and the underwings, they’re one of the most frequently observed and tracked groups of moths. There are moth’ers who are crazy about these groups but don’t pay a lot of attention to the smaller, less striking groups. This one was about three inches across or so.

Ruby Tiger Moth

That same night I got this very orange, fuzzy moth. This is a Ruby Tiger Moth. The tiger moths as a whole are generally a very fuzzy group. The adults have fur shawls draped across their shoulders, and (if you peek under their petticoat), furry undergarments. Even the caterpillars are fuzzy. The very common and familiar Wooly Bear caterpillar is a member of the tiger moth family (it becomes the Isabella Moth, a gentle beige moth, very toned down compared to its boldly-pattered larvae). The Ruby is found throughout the northern states and nearly all of vegetated Canada (barren polar ice sheets excepted).

Agreeable Tiger Moth

This is another tiger moth, this one the Agreeable Tiger Moth. I’m not sure what specifically about it makes it Agreeable, but it did seem like a very laid back, cooperative moth while I was photographing it. There are a whole bunch of white tiger moths, which are very beautiful in their simplicity and purity. One of my favourite things about many of them are their thighs – in this case, an orangey-brown, but in some they’re bright pink or orange.

Lappet Moth

And then the week before that, back in early May, I had another pretty good night at my moths, catching a number of new species for me, including this one, the Lappet Moth. The great thing about starting out in something is that everything’s new and exciting. This is not an uncommon moth, but I was nonetheless stoked to catch it because of its really neat appearance. The flanges on its sides are actually the hindwings poking out from under the forewings. It’s found throughout North America, feeding on a variety of deciduous trees.

6842 - Straight-lined Plagodis - Plagodis phlogosaria

One last moth to share today. This one, caught the same night as the Lappet, is a Straight-lined Plagodis. I got a second one the following week, as well. Another species found throughout North America, it’s associated with deciduous and mixed forests, the larvae feeding on a number of deciduous tree species. BugGuide.net, one of my primary online reference sources for identifying insects, indicates that it’s also called The Scorched Wing, as stated by the University of Alberta’s entomology department. I rather prefer this latter name myself. There are many moths with very colourful and creative common names, yet another thing that appeals to me about moths. That said, there are some great bird names, too, especially when you get down to the tropics.

Cocoons, big and small

Argyresthia thuiella? cocoon

I’ve had this cocoon sitting around since mid-March, a loose end without a blog companion to parade the web with. I also didn’t know what it was, although I imagined a Google search would turn something up quickly enough. However, recently I had two things happen. The first was I finally received my copy of Stephen Marshall’s book Insects (the first copy that was sent was lost by Canada Post, something I’ve never personally had happen before; the seller was kind enough to courier the second parcel overnight – I didn’t specifically need it overnight, but I thought it was a nice gesture). In flipping through it recently I came across practically the exact photo of the little cocoon I’d taken. The second was that I got some partnering photos to post it with. They’ll come next.

This first one, above, is the itsy-bitsy cocoon of a cedar leaf miner. It’s one or the other of a couple moth species from the genus Argyresthia that occur around here, but likely Argyresthia thuiella. This little moth is tiny. You can tell just by looking at its cocoon that it’s going to turn into a small moth. It has a wingspan (not length) of about 8mm as an adult. I happened across it while looking for bagworm moth cases (I didn’t find any), and just by chance spotted a little dash of white on the underside of a cedar branch.

You can notice the dead brown sections of cedar “leaf” nearby. These are areas that have been mined by the larva of the moth. On a deciduous leaf you’d see little trails, but the structure of the evergreen leaf hides it. Larvae overwinter inside the mined tunnels, then come out to pupate in late March or April, with adults emerging in May to June and hanging around for a couple months. They lay eggs mid-summer, and the larvae, once they hatch, spend the rest of the fall munching on cedar leaves. They overwinter in the tunnel and the cycle begins again. I gather that at the peak of their flight season, approaching a cedar where they’re gathering and laying eggs can result in momentary clouds of moths as they take off at the disturbance and swirl before landing again.

Polyphemus moth cocoon

This second photo I encountered while tracking the Yellow-bellied Sapsucker at TTPBRS last week. It’s the cocoon of a silk moth, I’m pretty sure a Polyphemus Moth. I know that the Polyphemus occurs down there because several years ago, in the first fall season I was volunteering there, we found one of the caterpillars dangling in a mist net, either having fallen off a branch above, or dropped by a bird when the bird that was carrying it flew into the net (there was no bird in the net, so if that was the case, the bird had escaped by the time we checked it). We took the caterpillar home with us, curious about what it was. Shortly after bringing it home it spun itself a cocoon, which sat for some time on the top of a dresser. When it finally emerged, it had turned into a beautiful, big, rich brown moth with gorgeous big eyespots on its hindwings. In sharp contrast to the previous moth, this one has a wingspan of nearly 6 inches.

The name Polyphemus comes from the mythical cyclops with the same name, mentioned in The Odyssey by Homer, and presumably refers to the moth’s giant eyespots. It’s the most common and widespread of the silk moths found pretty much across the continent north into southern Canada. There’s a neat series of photos of a newly-emerged adult moth at BugGuide.net. When a moth or butterfly first leaves its cocoon its wings are small and crumpled. The moth then has to pump haemolymph (the same blood-substitute body fluid that the jumping spider uses to jump) into its wings to extend them before they dry. If they dry before they’re fully filled out, or if the moth is in cramped quarters without room to extend them, the wings will be deformed and the moth most likely unable to fly.

Mystery cocoon

This last one… I don’t know what it is. When poking around the sides of the building at TTPBRS (the same building where I found the jumping spider), I found dozens of these little coils of sand grains stuck to the walls. They weren’t especially clustered, although they did seem to mostly be on the south and west sides of the building (the sunny sides). They’re only 7-8mm in diameter. I thought they were the neatest little things, and whatever made them had to be fairly common. The closest thing I could find was the cocoons of antlions, which make spherical balls of sand, but they’re found actually in the sand, not stuck to a wall, and they’re round, not coiled. I posted an ID request to BugGuide.net, and will add an edit if I figure it out.

Edit: I have an answer! The folks at BugGuide.net have come through: it’s the cocoon of the Snailcase Bagworm, Apterona helix. It belongs to the same family, Psychidae, as the bagworm moth I posted about previously. It was accidentally introduced to North America from Europe in the 1940s, and is now found in many states and provinces on both sides of the continent. The coolest thing about this species is there’re no males – the females reproduce parthenogenically (unfertilized eggs). Also cool, the adults are wingless, and the moths spend their entire lives within their case, only crawling out once they’ve laid their eggs, at which point they die.