Craneflies (Tipula paludosa, Tipula oleracea) are large, long-legged flying insects, sometimes called mosquito hawks because of their similarity in shape to the blood-drinkers, and the mistaken idea that craneflies eat mosquitoes. Craneflies have no mouth parts, and live as adults just long enough to breed.
It is the young larva, known as leatherjackets, that do all the eating. Leatherjackets are grey-brown and grow to between one half and three cm. Leatherjackets are easily differentiated from white grubs. Leatherjackets have no visible head, are brown, live just above the soil, and do not usually curl up into a C-shape. The leather jackets chew on the crown of the grass plant, which is where the blade grows from. The grass blade topples over and dies like a lumbered tree, and the leatherjacket moves on to the next grass plant. With enough of them in your lawn, you end up with large dead patches of ‘stubble’.
Adult craneflies are active from the beginning of June through the end of August. They are not good fliers, and you will often see them rising from the lawn as you mow it or near outdoor lights after dark. A few here and there is not a concern, but if you are finding them swarming around, call a professional. They are breeding and will soon be infesting your lawn with hundreds or thousands of leatherjackets. LawnSavers has an effective treatment for managing leatherjackets that will minimize any damage.
Rain forces leatherjackets out of the soil and often washes them off to hard surfaces like this roadside.
How bad can they get?
These leatherjackets washed out of a lawn after a heavy rainfall. A healthy lawn can withstand at least 20 leatherjackets per square foot, but populations can explode quickly and create devastating numbers before you even know it! Nematodes used for Grub management will NOT control leatherjackets. Nematodes are always species specific in their targeting. LawnSavers has the correct strain of Nematodes to control these larvae. Applications should be scheduled by the middle of October for best results!