Tuesday, March 15, 2016
The annual crane fly invasion
The crane fly family is one of the most diverse families of true flies. There are over 1500 different kinds found in North America.
The common name "mosquito hawk" is sometimes given to these flies; however the name usually comes with the belief that these insects are predators, perhaps on mosquitoes. Nothing could be further from the truth. Crane flies are among the gentlest of insects. Some are nectar feeders, sipping sweet sugars from plants and possibly helping out a little with pollination in the process. Other species lack mouth parts entirely. Instead, the adults of these species live out their short lives relying on fat reserves built up during their underground larval stage.
Crane fly larvae are rarely seen by all but the most dedicated (nerdy?) naturalists. These long, legless, worm-like creatures may be found in many types of moist soil, sandy areas along streams, rotting vegetation, mosses, or even feeding on organic matter in the nests of birds and mammals. Very few are considered pests, though the European leatherjacket can be a pest of turfgrass.
Your customers may be seeing crane flies and thinking that the mosquitoes are coming out larger and earlier every year. But crane flies are generally active before our pest mosquitoes. They can be distinguished from mosquitoes by their generally larger size; but also by their wings, which lack the scales found on mosquito wings. Close examination of the thorax with a hand lens will also show a V-shaped suture just behind the wings.
So what is good about crane flies? They are undoubtedly greatly appreciated by hungry birds at this time of year, as well as smaller mammals, fish, spiders and predatory insects.
There is no practical control for crane flies since they emerge from a variety of breeding sites and fly into backyards regardless of pest control measures. Instead, perhaps we should encourage our customers to "enjoy" crane flies while they last.
Some of your customers may think more kindly of these gentle and harmless insects when they learn that they only have love on their tiny minds. The sole activity and goal of the adult crane fly is to find a mate and, for the females, to lay eggs for next spring's crop of flies. And who wants to get in the way of love?