As kids, we called them mosquito eaters, mosquito hawks, skeeter eaters, and mosquito lions. Unfortunately, crane flies do not eat mosquitoes. Surprisingly, they can be lawn and garden pests.
Spindly legs and quiet demeanor have probably protected more crane flies than deserve it as they cling to our walls and ceilings. Frequently allowed to remain in a home or on a patio because they were believed to eat mosquitoes, most adult crane flies don’t eat at all. Those that do, generally only eat nectar. Their offspring, however, are another story all together. There are two types of crane fly found in California: the marsh crane fly (Tipula oleracea) and the European crane fly (Tipula paludosa). Globally, there are over 15,000 different types of crane flies.
Crane fly lifecycle
Like most flies, crane flies have a multi-stage lifecycle that goes from egg, to larva, to pupa, to adult. Crane fly pupa do not feed. Instead, starting around May, they lie under the surface of the soil as an adult develops within. In late summer, adult crane flies emerge. Adult females mate and lay eggs within 24 hours of emerging from their pupal stage. Eggs are laid in the soil, underneath lawns and pastures, in late summer and early fall. Those eggs hatch, releasing crane fly larvae into the soil. Crane flies are often found near creeks, streams, and leaky sprinkler systems.
Crane fly larvae
Crane fly larvae are much tougher than most other larval forms. They are so tough that they are called leatherjackets. Leatherjackets feed on the roots, root hairs, crowns, and leaves of your lawn and other members of the grass family (Poaceae or Gramineae). This includes corn, wheat, barley, millet, lemongrass, oats, sorghum, and rye. Feeding continues through the fall until winter arrives, weakening plants and making them susceptible to other pests and diseases. During the coldest months, crane fly larvae hibernate in the soil. As soon as temperatures start to rise, they take up feeding again. During the day, the larvae mostly feed underground. On warm, damp nights, they may emerge to feed on the aboveground parts of your grass plants. Lawn damage is most commonly seen in March and April as dry patches.
Crane fly controls
Crane flies have many natural enemies, such as birds and predatory ground beetles. Heavy crane fly populations can be treated by drenching the infested area with Steinernema feltiae nematodes. These cultural controls can help reduce the damage caused by crane flies:
Crane flies are not a big problem in most backyard gardens. That being said, I can’t help cringing when I hear people share misinformation. While a stream side crane fly larva may end up eating a mosquito larva, crane flies, as a group, are not the Skeeter Eaters of our childhood.
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.