Wednesday, November 4, 2009

Pumpkin Bugs

This year I actually carved a jack-o’-lantern for the first time in decades. My landlady had purchased several pumpkins and then had a carving party on Saturday, October 24. Since I’m a football fan, and I’m in New England, I carved mine in the form of a Patriots helmet. It turned out pretty well, and I had fun doing it. Once we set the hollow gourds out on the porch, though, insects began flocking to the fermenting fruits. By Halloween day, a surprising variety of critters could be found outside and inside the pumpkins.

October 31 was an unseasonably balmy day here in South Deerfield, which probably had a lot to do with the buzzing insect population. Among the more interesting visitors was this little “jumping plant louse,” in the family Psyllidae. Psyllids are related to aphids, and a few can be pests in their own right. They are quite tiny, but under magnification can be quite colorful and lovely as well.

The psyllid’s kin, aphids, were also out and about, drifting on the wind and alighting wherever their feet found purchase. This is the time of year when aphids are winged, seeking the alternate host plants where they will overwinter. While some species pass the cold months as adult insects, the majority probably lie dormant in the egg stage.

Not surprisingly, flies made up the bulk of the visitors to our big orange globes. Fruit is fruit, and even if the inside of a jack-o’-lantern must seem like a domed stadium to “fruit flies,” they treated it like a bunch of overripe bananas, carrying on their courtship dances and lapping up the liquid residue. These are actually “pomace flies” or “vinegar flies” in the family Drosophilidae, and not true fruit flies (those are in the family Tephritidae and they attack fresh fruit, wreaking economic havoc on growers). The adult female pomace fly lays her eggs in the decaying fruit and the larvae that hatch feed mostly on the yeast that is carrying out the fermentation process. The maggots can really hold their liquor and quickly mature in the alcoholic mess.

Larger flies were to be found as well, including vivid metallic “green bottle” blow flies in the family Calliphoridae, and flies from the family Muscidae (house flies and kin) were chief among them. Oddly, even this parasitic fly of the family Tachinidae visited. Tachinids are, as larvae, mostly internal parasites of other insects. Some tachinids are very “host specific,” meaning they attack only a handful of host insects, often caterpillars. Other species are “generalists,” and just about any old caterpillar will do. It is essentially impossible to identify tachinids beyond the family level unless you are an expert specializing in that incredibly diverse family.

Maybe my favorite fly of the day was this pumpkin-orange Homoneura fly in the family Lauxaniidae. You can see more detailed images of these little beauties on the Bug Guide page for the genus.

I can’t think of a better way to share a pumpkin than with the insect world. While we humans admire the glowing spheres cut in familiar, humorous, or scary patterns, the insects remind us that there really is such a thing as reincarnation, if not in spirits, then in the molecule-by-molecule recycling of pumpkin flesh into fly flesh. I, for one, kind of like that idea.

2 comments:

  1. This just proves, once more, that ecology is around us every day, even in the strangest of small ecosystems: the pumpkin. Fascinating post.

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  2. Only you could turn a decaying pumpkin into magic.

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