Botfly Puparium
Congratulations on some very creative guesses! Yesterday’s post was a botfly puparium – a hard case made from an insect’s larval exoskeleton (skin) that covers and protects the pupa. Most insects that go through complete metamorphosis (egg, larva, pupa, adult) don’t have this added protection for their pupal stage, but certain flies, including botflies, do. Botflies are fairly large, hairy flies that resemble bumblebees and are internal parasites of many species of mammals, including humans. Depending on the species, the botfly deposits its eggs on or near the host animal, or on another insect, such as a mosquitoe or housefly, which carries them to their host. The eggs of some species of botflies are ingested or inhaled; those of other species hatch and the larvae bore into their host. After entering and crawling around inside of the host animal for a week or so, most species of botfly larvae settle in a spot just under the host’s skin and remain there for three to ten weeks, consuming the flesh of its host. The lump, or “warble,” that forms just under the host’s skin where the botfly resides increases in size as the larva grows. A tiny hole chewed in the skin allows the larva to breathe, and eventually it exits through this hole. The larva falls to the ground, where it pupates in the soil and later emerges as an adult botfly. (The two yellow bumps at one end of the puparium are spiracles, through which the pupa breathes.) The whole story of this particular puparium is that Jeannie Killam found it in her old farmhouse’s kitchen cupboard, where it probably popped out of a visiting mouse. (Illustration is of a human botfly.)
Moose Flies and Moose
My recent quest for finding moose was successful – and my most striking observation, other than their imposing size, was the presence of a multitude of flies on and around the hindquarters of every moose I saw. I assumed they were deer flies, but they didn’t appear to be bothering the moose and research revealed that, in fact, they were moose flies, Haematobosca alcis. These flies can be seen throughout the spring and summer in dense swarms over and on the rumps of moose — five hundred or more may accompany a single moose. Unlike most other biting insects, both male and female moose flies feed on their host’s blood. Although not considered a serious pest (moose tend to pay little attention to them), moose flies may be responsible for sores often found on the hind legs of moose. It is thought that female moose flies may be stimulated by gases released by the moose when it is defecating, after which the female flies descend and deposit eggs into crevices in the moose’s scat.
Parasitic Flies
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There is a family of flies, Tachinidae, which consists of different species of parasitic flies, one of which is Epalpus signifier. If you look at enough dandelions this time of year, you are likely to spot one — their white rump is a distinctive identifying feature. This fly is technically a parasitoid, and as such, spends most of its life attached to or within a host organism (Noctuid moth caterpillar) , getting nourishment from it. Unlike a parasite, it eventually kills or consumes its host
Larvae-seeking Downy Woodpeckers
12-3-11 Larvae-seeking Downy Woodpeckers
When cooler days arrive and adult insects become relatively scarce, insect-eating birds are very clever at gleaning the twigs, trunks and buds of trees and shrubs for overwintering eggs, larvae and pupae. Certain galls (abnormal plant growths that house and provide food for a variety of insects) are sought by specific birds. Downy woodpeckers seek the larvae of the Goldenrod Gall Fly (Eurosta solidaginis), which overwinter inside Goldenrod Ball Galls (formed on Canada Goldenrod, Solidago canadensis) before emerging as adults in the spring. A tiny1/4” to 3/8”-wide hole (and an empty gall) is evidence that a downy woodpecker had itself a meal!
Naturally Curious with Mary Holland 
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