In spite of the importance and diversity of flies, there are not many books, especially popular books, devoted to them. Perhaps the reasons are obvious: they are are small, often inconspicuous, and sometimes annoying (or worse). Often, when I tell people I work on flies, they skeptically and sometimes disgustedly repeat the word “flies?” as if that is the most unthinkable group of insects to which one could devote their attention.
Certain people, the hardcore dipterists, however, truly love flies, and some few can convey that affection to the public. It takes a mixture of delight, quirkiness, and sometimes downright dark humor to unlock the secrets of this hidden world and make it available to the non-scientist. Few have tried, but one of the most successful to date is the British dipterist Erica McAlister, whose recent book “The Secret Lives of Flies” is required reading for all fly aficionados.
I am just returning home from the Entomological Society of America meetings, where I had the great pleasure of hanging out with some of the members of the “Diptera tribe” who came to deliver talks, exchange ideas, meet the newest crop of students, and discuss future plans. I got to spend some time with Erica, as well as Vladimir Blagoderov, Brian Wiegmann, David Yeates, and Riley Nelson, and many of the upcoming students. All are accomplished dipterists, yet only Erica has written a book that will be of wide interest to non-dipterists. Buy a copy- you won’t regret it!
Some flies migrate, just like some birds and butterflies, but it is rarely recorded. In fact, this might be the first record of a flower fly (or hover fly) migration for North America!
It took place on April 20th, 2017, at beautiful Montana de Oro State Park. I was walking with my dear friends Marianne and Gary Wallace when Gary said “look at all those bees!” I looked, and realized that they were not bees, but flower flies, thousands of them. They were flying against the wind, in a northward direction, not stopping at all. I actually got some video of this migration; have a look.
The flies look like bullets going by. We didn’t have any collecting gear (duh, it’s a park), but we tried knocking some down, to no avail. They were moving fast and avoiding contact. I tried taking some stills, and this is my best (bad) photo:
Why would syrphids migrate? These flies feed on aphids as larvae, and aphids are found on tender new growth. California’s rainfall comes during a short time in the winter, and then things dry up. An hypothesis is that as the more southerly vegatation dies off from lack of water (and thus also the aphid supply dwindles) the flies move northward looking for green, still tender fields, well stocked with their aphid food.
This was something I never expected to see, but wanted to record so others could keep their eyes open for it in the future. I’ll be back next year looking for them at the same time of the year, hopefully to learn which species they are.