Mosquito hawks, more accurately known as crane flies, are often mistaken for mosquito predators. However, it is their larval stage—commonly called leatherjackets—that can cause significant damage to lawns and turf.
These larvae feed on grass roots, leading to thinning lawns and dead patches, particularly in moist environments.
The Gentle Giant: Mosquito Hawks (Crane Flies)
The Mosquito Hawk, technically known as the Crane Fly (Family Tipulidae), is one of the most misunderstood insects in North America. Often mistaken for a “giant mosquito,” these leggy fliers are frequently found bobbing against window screens or porch lights during the spring and fall across the United States. Despite their intimidating nickname, they are completely harmless to humans and pets.
The Great Misnomer: Do They Eat Mosquitoes?
Contrary to popular belief, adult Mosquito Hawks do not eat mosquitoes. In fact, most adult crane flies do not eat at all; they live for only a few days with the sole purpose of mating and laying eggs. The few species that do feed typically consume only nectar or sugar-rich liquids. Their fearsome reputation is purely based on their appearance, which resembles a mosquito on a massive scale.
Identification: Crane Fly vs. Mosquito
It is easy to tell the difference once you know what to look for. Crane flies are significantly larger, often reaching a leg-span of 2 to 3 inches. Unlike mosquitoes, they lack a piercing proboscis (stinger) and are clumsy, weak fliers. They also possess a distinct V-shaped suture on their thorax and small, knob-like structures called halteres behind their wings, which act as gyroscopes for balance.
The “Leatherjacket” Stage
While the adults are harmless, the larval stage—known as a Leatherjacket—can be a minor turf pest in the U.S., particularly in the Pacific Northwest and Northeast. These larvae live in moist soil and feed on the roots of grasses and decaying organic matter. In high concentrations, they can cause small brown patches in lawns, but they are generally considered beneficial decomposers that help aerate the soil.
U.S. Homeowner Management
Since adult Mosquito Hawks are essentially “accidental” indoor guests, management focuses on exclusion rather than eradication. In the U.S., they are attracted to the yellow and white spectrum of outdoor lights. Switching to “bug lights” (yellow LEDs) can reduce their presence on your porch. If one enters your home, simply catch it in a cup and release it outside, as it poses no threat of biting or spreading disease.
Identification
Larvae are gray-brown, legless, and leathery in texture. Adults resemble large mosquitoes but do not bite.
Damage
Damage includes root feeding, leading to weak turf that can be easily pulled up.
Control
Control includes proper lawn care, reducing moisture, and applying biological treatments such as nematodes.