Large, spindly flying insects often referred to as “mosquito hawks” can become a nuisance around the home. Effective management requires proper identification and targeted control measures focusing on both the visible adult population and their source. This guide outlines strategies for managing these insects and reclaiming your outdoor living space.
Identifying the “Mosquito Hawk”
The insect commonly called a “mosquito hawk” is the Crane Fly, a member of the Tipulidae family. Adult crane flies are harmless to humans; they do not bite, sting, or transmit disease, and most species do not feed, surviving only to reproduce. Their appearance, featuring long, fragile legs and a body similar to an oversized mosquito, leads to frequent misidentification. The adult life stage is brief, lasting only a few days to two weeks, and is spent laying eggs in moist soil. The actual damage is caused by the larval stage, known as leatherjackets, which are thick-skinned, brownish-gray grubs that feed on the roots and crowns of turfgrass.
Controlling Adult Populations
Although harmless, adult crane flies are a nuisance due to their numbers and attraction to light sources. A primary method for immediate reduction is light management, as these insects are highly phototactic and congregate near exterior lighting after dusk. Switching outdoor bulbs to yellow-spectrum or low-UV sodium vapor lights significantly reduces their attraction to entry points.
Physical removal offers an immediate, non-chemical solution for adults that enter the home. Simple sticky traps placed near windows or light fixtures capture them effectively. For insects inside, a vacuum cleaner with a hose attachment provides a quick removal method. Adult control focuses on deterrence and physical capture, limiting the number of females that successfully lay eggs in the lawn.
Eradicating the Larval Source
The most effective, long-term solution is to eradicate the larvae, or leatherjackets, that live in the soil. These larvae are responsible for the subsequent adult population, and their feeding habits cause noticeable damage to lawns, resulting in brown patches of dead turf. Control efforts must focus on the soil environment where the larvae are most vulnerable.
Cultural/Maintenance Control
The European crane fly prefers to lay eggs in soil that is consistently moist. Reducing excessive lawn watering and ensuring proper drainage makes the environment less hospitable for egg-laying and larval survival. If irrigation is necessary, watering deeply and infrequently in the morning allows the soil surface to dry out before evening, disrupting the environment the adults seek.
Maintaining a healthy lawn through regular aeration and thatch management also makes the turf more resilient to the larvae’s feeding damage. Aeration improves soil oxygenation and drainage, while a nitrogen-rich fertilizer application in the spring helps the grass recover from root injuries. A dense, vigorous lawn can often tolerate a low-level infestation without showing significant damage.
Biological Control
Beneficial nematodes offer an effective, organic method for controlling leatherjackets without harming people, pets, or beneficial insects. Species such as Steinernema feltiae and Steinernema carpocapsae are microscopic, parasitic worms that seek out the larvae in the soil. Once inside the larvae, the nematodes release a symbiotic bacteria that kills the pest.
Application timing is crucial for the success of nematode treatment, as the larvae must be actively feeding and close to the soil surface. The optimal window is typically late summer to early autumn, around August through October, when the newly hatched larvae are small and most susceptible. The soil must be moist before and after application, as the nematodes require water to move through the soil profile and locate their hosts.
Chemical Control
For severe infestations where the density of leatherjackets exceeds an estimated 25 per square foot, chemical options may be considered. These insecticides target the larvae in the soil, and specific active ingredients include chlorantraniliprole, bifenthrin, and carbaryl. Chlorantraniliprole is often favored for its low impact on beneficial insects, while bifenthrin and carbaryl are broad-spectrum options.
It is important to check the product label to ensure the insecticide is registered for crane fly larvae control and to follow all application directions precisely. Chemical treatments are most effective when applied at the correct time of year, typically in the spring when the larvae are actively feeding and causing the most visible turf damage. Using soil-targeting treatments prevents the problem from maturing into an airborne nuisance.