These insects are a common food source for birds, and unjustly feared by people. Let’s get to know them!

Introduction to Crane Flies

Crane Flies are a great way to illustrate the diversity of our local bugs. This suborder of flies is abundant across Pennsylvania, and is an insect group unjustly feared by people. They’re important in my yard where warblers fuel their migration and chickadee parents feed them to their nestlings. Dr Chen Young, Carnegie Museum of Natural History in Pittsburg (now retired), completed a comprehensive survey of crane flies in PA in the 1990s. He determined that in PA we have 400 species possible, with 300 species observed in the field. That’s more than the number of bird species in PA from all bird families!

Crane fly on flower
Crane fly nectaring on potentilla (Limonia species)

Importance of Crane Flies

Most crane fly larvae (aka leatherjackets) are aquatic, but moist leaf litter can be sufficient. A few species are terrestrial and found in dry habitats including decaying logs. Crane fly larvae live up to a year, and are important feeders of fungi and dead or dying organic matter, aiding in the process of decay. Because many adults are eaten in a location away from the wetland ecosystem where they develop, they return nutrients to drier areas.

In Arctic tundra habitats, crane flies (along with spiders) dominate the fauna and are an important part of the survival of artic breeders like sandpipers and their nestlings. Locally, crane flies are beneficial as a food source to amphibians, reptiles, and fish in addition to birds.

Beautifully patterned crane fly (Epiphragma fasciapenne)

Telling Crane Flies from Mosquitos

Despite being large and common, few people know what a crane fly is. In fact, they are often misidentified as giant mosquitos and scare people with their long legs that resemble daddy longlegs or cellar spiders. Crane flies are harmless to humans, and as you will soon see, are important to birds and ecosystems.

So how do you tell a crane fly from a mosquito? Here are some clues:

  • Crane Fly – Big body – typically 1/2-2 inch, mouth is a snout or beak, long gangly legs
  • Mosquito – Small body – typically < 3/8 inch, tube shaped mouth to pierce prey (female), highly plumed antenna (male), hind leg may be upturned or striped

If it’s buzzing your head and lands on you then it’s probably a mosquito!

Head and mouth of crane fly (Tipula)
Female mosquito
Woodland crane flies often mistaken as mosquitos

Finding Crane Flies

Adult crane flies can be found almost anywhere, but are more frequently found near streams or ponds. As adults, their primary objective during their short 1-2 week life is procreation. Some adults don’t even feed. During the day, I often find adults resting in vegetation on woodland edges. They spook easily, but are weak fliers so you can often follow them – easy prey for a chickadee. Many crane flies are attracted to lights at night. If you have a porch light on, look on the ceiling or side of the building near the light. And of course, don’t forget to look in the mouths of birds. Happy Crane Fly hunting!

Karen Campbell, a member of Lehigh Valley Audubon and of provided the content and photographs for this article.

Carolina chickadee with crane fly for nestlings
Hanging from its long legs in the understory
Crane fly hiding under flower