Adult crane flies lay eggs in the soil from mid-July to late September. The larvae hatch and begin feeding on roots in the fall. They over-winter in the soil and resume feeding in the spring. They do the most feeding during April and early May.
The larvae remain in the soil to change into an immobile stage, called a pupa. Inside the pupa, they transform into adults, which emerge from mid-July onwards.
The adults of a similar crane fly species emerge from May onward.
Leatherjackets rarely damage residential lawns.They can damage closely mowed, highly managed or stressed turf, particularly in cool, wet summers.
Even where their feeding has caused noticeable thinning, lawns quickly recover as soon as leatherjackets stop feeding in May.
More damage may be caused by birds and raccoons that dig up the lawn to eat leatherjackets.
HOW CAN I PREVENT DAMAGE?
A healthy, deep rooted lawn quickly fills in and outgrows root-feeding by leatherjackets. To keep the turf dense,sprinkle turf grass seed over thin areas in February and March.