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Funded by National
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Species of the genus Melaloncha are among the most interesting of all phorid flies. Found almost exclusively in the Neotropical Region, they are internal parasitoids of a number of species of bees, especially stingless bees. The flies are among the most brightly colored and attractive phorids, with various species having contrasting dark and yellow to orange patches, metallic, greenish-blue eyes and abdominal patches of reflective, silvery pollinosity. They are of relatively large size, in the 3-6mm range, which, combined with their bright colors, allows them to claim the title of being the "butterflies of the phorid family." |
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The way of life of most species is unknown, but all are believed to be parasitoids of bees, with the known hosts being stingless bees, bumble bees and the introduced honey bee, Apis mellifera. Female flies attack the bees either while they are foraging on flowers, or near their nests. We have recently discovered that the flies use a variety of methods to attack their hosts, but many of them curl their ovipositors under the abdomen, up between the legs so that the point of the stylet is extending beneath the head (see photos). The fly then rushes forward towards a bee and jabs her ovipositor into the bee's body, injecting a single egg. This happens extremely quickly and is difficult to observe, but it appears that the eggs are laid in the head or the thorax. Some species attack the bees while they (the flies) are flying- these species usually lay eggs in the host abdomen. In either case, the fly larva hatches from the egg and consumes the internal contents of the bee, eventually killing it. |
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Bee-killing flies are considered to be rare, because there are few specimens in collections and because there are relatively few species. Only thirty-two species of bee-killing flies are described, but there are many more awaiting discovery. In Costa Rica alone, we have collected over 50 species, and we estimate that in the entire Neotropical Region there are over 200 species in total. We have devised a new method of collecting these insects, and have greatly increased the number in collections. |
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One aspect of bee-killing fly biology is of intense interest to many people: some species of these flies attack and kill domestic honey bees. Some researchers have found high bee mortality from these flies, but because Melaloncha do not destroy colonies, their effects might not be noticed. Certainly, tropical beekeepers should keep their eyes open for lurking Melaloncha females. Those beekeepers who tend to native stingless bees should be even more vigilant. |
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