Category: invertebrates

I’m still working my way through the photos I collected last week. It’s a good thing I got so many blog topics backed up, because since bringing the puppy home I’ve barely had any time to go out and take some more. These were taken Friday, just before heading out to get the pup. Friday was gorgeous. Beautiful temperatures, clear skies, and even though it was rather windy, the air was warm, not nippy. I could’ve stayed out all afternoon, if I didn’t have places to be. Since I did, I just stuck around the house, but I turned up a few things there so I was still happy.

These Small Milkweed Bugs (Lygaeus kalmii) were all over the sunny parts of the foundation. The concrete had warmed up in the sun, and they’d gathered there to soak in the heat. There were quite a few also in the dead vegetation, so I’m not sure whether the bugs had been wintering in cracks in the house, or tucked beneath all the vegetation on the ground. Given that last spring I would find them crawling around the dead grass in the meadow, however, I’m inclined to believe the latter.

It’s funny that, growing up, I never noticed them around, while out here they seem quite common. We had milkweed there, too, but not nearly the amount of it that we have here (in fact, I’m not sure I’ve ever seen an area with quite so much milkweed as here), so I wonder if it’s simply a function of food plant abundance. Or, perhaps, I just wasn’t that observant as a kid.

They’re easily confused with the Box Elder Bug (Boisea trivittata), which is actually what I thought they were at first (which is funny – I did the same thing last year). Box Elder Bugs will overwinter in the nooks of your house and are often encountered in large groups at the first thaws in the spring, so it would make logical sense. Small Milkweed Bugs share the black and red aposematic (warning) coloration telling predators they don’t taste good (the result of the toxins in the milkweed seeds they feed on in the fall), but they have more red than the Box Elder Bugs. The pattern of the red creates a heart shape of the black on its back.

Of course, there’re not many milkweed seeds (their dietary item for which they’re named) to eat at this time of year. During the early spring, the bugs can get by scavenging dead vegetable matter and detritus or even preying on other insects. They switch to nectar once flowers start blooming, which carries them through the summer. When you’re most likely to notice them, though (assuming they don’t start crawling over your house foundations in the spring) is during the late summer and fall, once the milkweed pods develop. Then both they and their nymphs can be quite common on the plants.

I have been seeing these things around our property since moving here. Initially there were just a handful of them, in the Rubus canes along the edge of the woods. I took a photo last winter, the first time I found one. I came home, tried to ID it, couldn’t find anything that quite matched. I found another this fall. Took a photo, came home, tried to ID it, came up blank. A few weeks ago I came across another, same thing. Each time I was sure that I just hadn’t been using the right search term, or looking in the right place, or something like that.

Then earlier this week I found a whole patch of them, in a thicket of canes over at the 100-acre woods. There had to be more than a dozen, clustered into just a few square meters. “Okay,” I told myself, “I really need to get these figured out.” I ran off a bunch more photos then came home, made myself a tea, and forced myself sit down and look till I had an answer. Worse came to worst, I figured, I’d post it to BugGuide and hope Charley Eiseman would help me out on this one, too. ;) But it’s so much more satisfying (and you remember better) if you can identify it yourself.

I think what had been causing me problems is I’d been looking for a photo match. This has always done me fairly well before. Go to Google image search and type in some sort of descriptive term, and in all likelihood someone else has described and ID’d the same thing you have. This didn’t work in this case. It pulled up quite a number of lumpy galls, but none of them looked to be the same as mine. I also tried my favourite recent reference acquisition, Eiseman & Charney’s Tracks & Sign of Insects (go get a copy, if you haven’t already! You’ll thank me!), but none of the photos there looked like my thing, either (though some looked similar). I repeated this process in each ID attempt, and again this week.

It was only on this most recent try that I finally delved into Eiseman & Charney’s text, paying close attention. And it was in there that I think I found my answer. I found three references to galls in brambles (Rubus sp.).

The first stated, “Metallic wood-boring beetles (Buprestidae) include the red-necked cane borer (Agrilus ruficollis), responsible for slight, ridged swellings that are 1 inch (2.5 cm) long in bramble canes”. Which, as cool as it would be for my galls to be wood-boring beetles, didn’t seem to be it. They’re more lumpy and large than slight and ridged, and most are longer than just an inch.

Number two said, “Woody stems and twigs are host to a number of Neolasioptera midges … N. nodulosa [is responsible for] swellings on brambles, sometimes ridged and usually near the tip of the stem.” This seemed a definite possibility. None of them were ridged, but the text only said “sometimes”. Many (though not all) of mine were near the tip. So I Googled it. They definitely do make swellings on bramble canes, but they seem to be much slimmer than what I have. Hm. Back to the book.

The final reference read, “Several species of Diastrophus (Cynipidae) cause pronounced swellings on blackberry stems (as well as roots), up to 6 inches (15.2 cm) long.” I’m not sure which species of Rubus is referred to by “blackberry” (there are at least two that could be called such), but they’re the right plant genus, anyway. And these galls are definitely pronounced, and a couple of them did reach a few inches long. The BugGuide.net page for D. nebulosus looks pretty similar, and the text did suggest that there are several species, which may or may not necessarily all look the same.

So I think these are Diastrophus galls. The insects that made them are wasps. They look less like what we typically think of as wasps, and more like fruit flies – very squat in stature. The lumpiness of the gall is due to the presence of many chambers within. Presumably the adult female lays many eggs into the plant, all clustered together, and they all make their own swelling, which in turns creates one large, lumpy gall. There doesn’t seem to be very much out there on their life history, but from the circumstantial evidence of my observations it would seem they overwinter in their galls and emerge in the spring to mate.

Though the galls on our 30 acres were untouched, more than half of the ones at the 100-acre woods had been investigated by birds. Downy Woodpeckers and chickadees will both drill into galls to extract the grubs overwintering within. They’re most commonly known to do this with goldenrod galls, but obviously these Rubus galls were large enough and promising enough to draw their attention. Where the birds have chipped away the woody cover, you can see the dark holes belonging to each individual chamber. (And it was the discovery of this, more than the abundance of them, that made me really want to get an ID after finding the bramble patch.)

I love a good scavenger hunt. I love the challenge of hunting for something particular, given some guidelines on where to look, and the delight and satisfaction when the target is found. Which is probably why, every winter, I go out one afternoon to see if I can figure out where the tent caterpillars are going to be this year.

It all started when I found a cluster of white eggs on the shiny dark bark of what I think was a young apple tree, in spring of 2008. It had always seemed to me that the white tents of the tent caterpillars appeared as if by magic in the spring. One month there was nothing, the next month there was this large, fist-sized webbing in the fork of a branch. So when I discovered that the moths lay their eggs on the branches – fairly conspicuously, I might add – and that they spend the winter in this state… well. A challenge, if I ever saw one.

That was 2008. Late in the winter of 08/09, I went out and scoured the branches of appropriate trees, deliberately trying to find the egg masses of the tent caterpillars before they hatched out in the spring and started building their webs, and was pleased to actually find some. I did it again last winter, too, though I only mentioned it in passing in another post.

And here’s this year’s cohort. The top photo is of last year’s eggs (laid 2009, hatched 2010). The second photo is of what will become this year’s caterpillars (laid 2010, will hatch 2011). Between laying and hatching, the eggs are covered by a shiny brown, hard shellac-like cover that helps to protect them from the elements and potential predators. When the caterpillars hatch in the spring, they’ll have to chew their way through this cover to get out. The shellacking falls away after this, leaving white eggs with dark holes in the tops – how you can tell the difference between old and new eggs.

After they hatch, the caterpillars move down the branch (toward the trunk) until they reach the first major fork. There, they set up shop and start building their web. This photo is of a clump of new eggs only a handspan above a major fork. I bet you can guess where the nest is going to be, come May.

Tent caterpillars are no more than an aesthetic nuisance – they very rarely cause any lasting damage to the tree – and so I leave them. Out here in our fields, there’s no one to be bothered by a defoliated tree anyway. Once the caterpillars move on to pupate, in late spring/early summer, the tree will have a chance to regroup and fix itself up again before it has to go dormant for winter.

I talked a bit more about tent caterpillar biology in my original post from 2008 (mostly post-hatching info).