One of the first recognizable signs of spring to anyone living in much of Texas is the swarm of crane flies that descend on urban and rural areas. Often referred to as mosquito hawks due to their Texas-sized, mosquito-like appearance, these flies are harmless, even though their entrance into homes is generally uninvited.
Bryant McDowell ’14, Texas A&M AgriLife Extension Service urban integrated pest management, IPM, program specialist with the Texas A&M AgriLife Research and Extension Center at Dallas, explains below what these flies are and how concerned people should be about them.
What are crane flies?
Crane flies are large, tan-colored, fragile flies with long legs that belong to the Tipulidae insect family and are related to other true flies. They generally appear in droves in the fall and spring of each year.
As adults, crane flies have very short lives, generally one week or two. Much of their lifespan is in the larval stage, where they can be found in moist soils, typically feeding on decaying organic matter. As larvae, crane flies are fairly protected from the elements and can live for upwards of three years in this stage.
When the environmental conditions are right, such as the rising temperatures we have been having recently, they pupate or hatch and begin emerging as adults. It is important to keep in mind that late cold spells may contribute to a decrease in the population of crane flies.
They usually appear earlier in the spring than other species of flying insects due to their fragile bodies and the fact that they are not the best fliers. This way, they can mate and lay their eggs when there are fewer predators around, ensuring the next generation’s survival.
I like to think of them as the robot vacuums of the insect world. They fly around until they hit something and then go off in a different direction.
Are crane flies harmful? Do they sting humans?
There is no need to fear crane flies. These insects are completely harmless, and quite fragile. In general, they do not feed as adults; their only purpose is to reproduce for the next generation. They do not possess a stinger, and most of them do not even have mouthparts as adults.
If adult crane flies are feeding, the males will feed on nectar sources for a good carbohydrate that provides energy for them to fly around looking for females.
Are crane flies good to have around?
Crane flies are a great food source for all sorts of insectivores, like frogs, swallows and armadillos, that are becoming more active as temperatures increase. They play an important role in a healthy ecosystem.
Do crane flies eat mosquitoes?
While many people refer to them as mosquito hawks or skeeter eaters, crane flies are not mosquitoes, nor do they feed on them.
What are crane flies attracted to?
Crane flies often fly around in grassy areas and water bodies, looking for mates and a place to lay their eggs.
They are also attracted to lights at night, which is how they often end up indoors. Ensuring window screens are in good condition, eliminating gaps around windows and doors, and keeping doors closed will be the easiest way to keep them out. If you find them indoors, they can be scooped up and placed back outside, or you can use a fly swatter on them.
Further information
McDowell; Molly Keck, AgriLife Extension, IPM specialist, Bexar County; and Wizzie Brown, AgriLife Extension, IPM specialist, Travis County, recently participated in a podcast about crane flies. It can be accessed here or on your preferred podcast platform.
AgriLife Extension also has information about crane flies in their Field Guide to Common Texas Insects as well as an Insects in the City blog post about them by Mike Merchant, Ph.D., retired professor and AgriLife Extension urban entomologist.
