Biology of New World Bot Flies: Cuterebridae

Maggots of cuterebrid bot flies are conspicuous, repulsive, and frequently encountered cutaneous parasites of mammals in the New World. These maggots, or bots as they are called, develop individually in a skin furuncle or open cyst (the warble) and at maturity back out through a hole in the skin (the warble pore), drop to the ground, and pupate. In temperate climates the pupa, within a puparium, overwinters. Adult cuterebrids rarely are seen or collected. They are medium to large (30 mm), robust, blowflyor bumble bee-like flies, often with dense lateral patches of colorful pile or pollen. Adult lifespan is relatively brief and is directed to mating, host seeking, and oviposition. These flies have excited interest in entomologists, mammalogists, and parasitologists for three hundred years. Knowledge of their biology is scat­ tered and fragmentary. Only in the past two decades have comprehensive field studies and laboratory colonization allowed detailed observation of their adaptive tactics and close, balanced relationship with mammalian hosts. The purpose of this paper is to review the biology of these fascinating parasites and to identify gaps in our knowledge. In so far as some of the taxonomy and economic importance of these flies relates to their biology, these areas are included marginally, but their complete review is beyond the scope of this chapter. This review treats successively the large genus Cutere­ bra, the monotypic but economically and medically significant genus Der­ matobia, and the four other cuterebrid genera, followed by a listing of cited references. The cuterebrid bot flies are a specialized line of calliphoroid or blow fly-like Diptera that are restricted to the New World. They evolved as specialized Calypteratae in the calliphorid-line of flies (30) in which sapro-