Crane flies are large (2.5cm), brown flying critters resembling very large mosquitoes. They are also called leatherjackets.
Crane fly adults-Natural Resources of Canada
You’ve seen them fly around at night in swarms in the spring. The larvae are light brown or grey caterpillars that cause major damage. Adults do not feed. Eggs are very tiny and shiny black. Pupae are brown and spiney.
Larvae (right)-Natural Resources of Canada, Larvae (left)-Minnesota Department of Agriculture
Habitat and Lifecycle
They occur in great numbers in coastal wet climates and are found throughout North America and many European countries. There are almost 300 different species. Females lay their eggs in the summer in the soft soil (usually a damp area), eggs hatch within 2 weeks and the larvae feed from early fall throughout the winter and into the spring. They pupate and the adults emerge in the spring and mate immediately. There is usually only one generation per year.
Damage on roots of seedling trees (left)-Natural Resources of Canada, Damage on lawn-Minnesota Department of Agriculture
Diet and Damage
They destroy many seedlings including trees, lawns, pastures, weeds, potatoes, cereals, alfalfa, and many other forage crops. They are a terrible nursery pest. They feed on the roots, tubers and bark of seedlings. Most times damage is servere enough to kill the hosts. These guys are truly evil.
1) Hand Pick – In the fall and in the spring lightly dig around the soil and pick them out. Look for them in marshy or moist areas. Flyswatters work well with the adults.
2) Control Moisture – Larvae like the moisture so good drainage practices is a must.
3) Natural Predators – Birds, parasitic nematodes and most ground beetles.
4) Sticky Traps – you can buy these or make your own with bright yellow card coated with a sticky substance like tanglefoot. They also can catch other pesky flying insects.
5) Maintain your lawn – Keep your grass at a minimum height since they like to hang around and lay eggs in high moist grassy areas. Good drainage is a must and your lawn must be healthy, so try a slow realease high nitrogen organic fertilizer.