What says “Halloween” better than a Jack-o–Lantern? You may be surprised to know how many insects are responsible for producing pumpkins, returning rotted ones to the soil, and afflicting them in between blossom and harvest.
Yes, honey bees pollinate the blossoms of pumpkins and other members of the gourd family, but the squash bee, Peponapis pruinosa, pollinates nothing else. Squash bees, in contrast to the social, immigrant honey bee, are native solitary bees. Each female excavates a nest burrow in the soil, stocking each underground cell with a loaf of “bee bread,” a pollen and nectar ball that will feed a single larva offspring per cell. You can often see male squash bees waiting at the bottom of a blossom for the chance to mate with a female that visits the flower for pollen and nectar. Squash bees are most active in the morning, so look for them then.
Not every insect in the pumpkin patch is there to foster healthy gourds. Squash bugs in the genus Anasa (family Coreidae or “leaf-footed bugs”) are a prime example. The sap-sucking feeding of large numbers of these insects can severely impact a pumpkin crop. Meanwhile, the caterpillars of the Squash Vine Borer moth, Melittia cucurbitae, feed inside the stems, disrupting the flow of nutrients and thereby weakening or killing the plant beyond the point of internal girdling. Striped Cucumber Beetles, genus Acalymma, cause damage in both adult and larval stages. Adult beetles feed on seedling plants in spring, then the second generation feeds on flowers and foliage of maturing plants. In between, larvae feed on the roots. They can also transmit the microbe that causes bacterial wilt, a devastating disease.
One you have carved your Jack-O’-Lantern, it starts decaying in the cool autumn air. Its flesh ferments and starts attracting things like “fruit flies.” The little tiny flies we call fruit flies are actually “pomace flies” or “vinegar flies” in the family Drosophilidae. The increasing alcohol content of the fading pumpkin attracts them and the larvae that hatch from the eggs laid by the female flies feed mostly on yeasts that attack the fermenting gourd. Other kinds of flies are also attracted to fermenting gourds, as are other kinds of insects.
While we humans admire the glowing spheres cut into familiar, humorous, or scary faces, the insects remind us that there really is such a thing as reincarnation, if only molecule by molecule, from fruit flesh to fly flesh. Happy Halloween!