The most beautiful phorid flies are in the genus Melaloncha, also known as bee killing flies. I have no small bias in this statement, however, since I worked on them for several years and grew to be very fond of them.
One of the allures of these flies was their rarity when I first started. In all of the collections I surveyed, I could find only a few specimens, about 100 in total. There were many new species among these specimens, however, so I knew that the 32 described species was only the tip of the iceberg. But how was I to uncover the rest of that iceberg?
Many parasitic phorid flies seem to be attracted to masses of their hosts. Logically, aggregations of hosts should create aggregations of parasitoids, so Giar-Ann Kung and I decided to try to make aggregations of stingless bees, the known hosts of these flies. Monty Wood, a fellow dipterist who works on tachinid flies, told me that when he sprayed a mixture of honey, Coca-Cola, and water onto undergrowth vegetation in an attempt to attract his flies often attracted huge aggregations of stingless bees instead. Therefore we tried spraying honey and water, and were almost immediately successful in attracting bees, and eventually flies. There was one other required condition, however: it had to be in the sunlight, or the flies would not be attracted. This is contrary to most phorids, which tend to be more active in shade.
Once we adopted the honey spray and sunlight combination, we started collecting large numbers of these flies, eventually collecting thousands of them. Sometimes, we were almost too successful in attracting the bees, producing gigantic aggregations that made it impossible to breathe or see anything, necessitating the use of jury rigged bee veils. These consisted of an insect net placed over the head and sealed around the neck with rubber bands. Eventually, though, the tiny stingless bees would get in, and we’d have to beat a retreat to get the annoying things out of our eyes, ears, and noses.
It was all worth it though, as we ended up catching 50-100 Melalonchaper day at good sites, and found almost 150 new species. I think there are still many more out there to find, so we keep spraying honey wherever we go in the tropics, and keep finding the beautiful, but deadly (to bees) bee-killing flies.