Tay Meadows Tidbit – Gypsy Moth eggs

Gypsy Moth egg mass on tree trunk

I’ve been back on the snowshoes since our big snowfall last week. Although the snow has been wet and sticky, meaning that it tends to pack to the lacings, the snowshoes are still a better option than just hiking “barefoot”, and the skis sink down into it too far to be practical. Although for a while it was possible to hike through the forest on the crusty snow cover, warming temperatures soon put a stop to that. The snowshoes gave me an opportunity to visit some of the areas I haven’t been to in a couple of weeks.

One such spot was a patch of trees, a peninsula of woods that juts out into our meadow from the neighbour’s forested land. I’ve walked through this patch numerous times since the fall. Yesterday I decided to go investigate some fungi I could see growing on the side of a snag.

The fungi was too withered and covered in algae to be able to identify, but while checking it out I noticed something else. Can you spot it in the photo above?

Gypsy Moth egg mass

It’s the egg mass of a Gypsy Moth. It’s slightly fuzzy and a soft cream colour. Inside all the fine hairs are little eggs, each about the size of a rainbow sprinkle. I’ve written about Gypsy Moth eggs before; in the first winter of this blog, when it was still a young month-and-a-half old, I photographed an interesting patch on a tree in the forest behind my parents’ old house (back when they still lived there), which I thought to be a slime mold. A reader corrected me, happily, and when I went back to look at it again I found several more.

Although Gypsy Moths have the potential to be extreme defoliators and serious forest pests, the sort of infestation that completely obliterates a forest canopy is rare. (Check out these posts at the Ohio Nature Blog for some startling examples of this.) In reality, the vast majority of the time Gypsy Moths are no worse a pest than any of our other numerous defoliators, such as tent caterpillars or fall webworms. The damage they do is usually more aesthetic than life-threatening for the tree, and unless the tree is already weakened due to disease or another infestation, it will usually bounce back quickly, putting out new leaves by the end of the summer.

Gypsy Moths aren’t native to North America; they were the result of a silk production experiment gone awry, and they’ve now spread over a large portion of the northeast. If you find some eggs in your area there’s probably no cause for immediate concern. I just left these where they were, as they were the only ones I could see. If you start seeing infestation levels, though, such as the crazy numbers in the Ohio Nature Blog’s post, might be worth contacting your local environmental authorities to see if it’s cause for concern.

Lymantria dispar - Gypsy Moth (male) - 8318
Male Gypsy Moth (females are larger and white)

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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.

Gypsy Moth egg mass

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.

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.

Gypsy Moth pupa case

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.

Gypsy Moth egg mass and pupa case

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.

Gypsy Moth laying egg mass

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.