Facts About Crane Flies

Adult European crane flies are also known as mosquito hawks or mosquito wasps. Many people believe that crane flies eat mosquitoes (hence the name mosquito hawk), but nothing could be further from the truth. In fact, European crane flies don't eat much of anything once they reach adulthood.

As an adult, crane flies are annoying and prevalent, but relatively harmless to your yard and garden. As larvae, or leatherjackets, crane flies are dangerous pests that can easily destroy entire lawns or gardens. Read on to learn more.


So... What are Crane Flies?

Crane flies are found all over the globe, from the tropics to the northern regions. These insects are true flies and make up over 15,000 species worldwide. The most common and most damaging in North America, hilariously enough, is the European crane fly.

The European crane fly resembles a mosquito in appearance, but is generally much larger (reaching up to 2.5 inches in wingspan). Crane flies are often yellow, brown, or gray. Their antennae are long and segmented (featuring up to 39 segments per antenna!).

The crane fly larvae, also known as leatherjackets, look like brown worms and cause the destruction to grass and turf. Eggs are long and round in shape and dark brown to black in color. The eggs may be deposited in clusters or groups and have been found in areas that include marine, brackish, and fresh water types, highlighting the versatility of the crane fly in surviving different environments. Crane flies do not eat in adulthood, only in the larval stage.


Reproduction Patterns of Crane Flies

During mid to late summer, within a day of emerging from pupating, the adult female mates and deposits her eggs in the grass found in lawns, pastures, golf courses, and other grassy locations. Interestingly enough, the female crane fly emerges from her pupa with fully mature eggs so that she can reproduce immediately.

When the eggs hatch, small brownish larvae appear that look like worms. These larvae are called leatherjackets due to their tough outer skin. The legless larvae, or leatherjackets, dine on grass and clover, as well as plant and grass roots--this destructive consumption of roots can lead to plant and crop death.

When winter comes, the larvae will overwinter and then in the spring continue to feed, causing visible damage to lawns and turf. The larvae will feed until the middle of May and then do not feed as they enter the soil to pupate during July and August.

At the end of August, the crane fly larvae will navigate to the top of the soil and emerge as adult European Crane flies. Although adult European crane flies live only briefly, the leathernecks may survive for over a year before becoming adults, all the while wreaking havoc to lawns and gardens.


Crane Flies' Habitat

The European crane fly is not native to the U.S., but since its unplanned introduction in the Pacific Northwest, it has become a significant lawn pest here. In the eastern and southern United States, the larvae are involved in organic matter transformations.

These insect pests prefer to be near water or areas where soil is moist and contains organic materials. In addition, scientists have noted that the larvae are also feeding on flowers, and certain fruits and vegetable plants. Their mosquito hawk colloquial name is a misnomer--crane flies do not eat mosquitoes or any other insects.

Adult European crane flies may be found around lights at night. New York and other northeastern United States cities have recently become infested by this insect pest.


Symptoms of Crane Fly Damage

If you have a crane fly infestation, your lawn or golf course may look "eaten" in parts, with uneven sections of grass completely devoured, leaving only brown soil. Lawns may have larger holes from where skunks and other grub insect predators have dug into the ground to find the crane fly larvae.

In addition, grasses may appear yellowed and unhealthy. Large numbers of these pests may land on the sides of your house, leading to unwanted nightly encounters with flapping flies dive bombing your face. Adult crane flies may also appear in swarms that rival the nastiest of gnats.


Results of a Crane Fly Infestation

Large sections of "bald" lawns may result from the feeding by the leatherjackets, or crane fly larvae. Grass may turn yellow or become thinned. Young grass is particularly vulnerable to these insect pests. Sometimes lawns and golf greens may need to be repaired or restored or replaced entirely as a result of crane fly damage.


Natural & Organic Controls


An effective method of controlling crane flies is insecticidal soap and pyrethrins. This method can be used safely if directions on the product are carefully followed. Sprays with pyrethrins paralyze the crane flies and result in their death.

In addition, using an effective grub killer that contains Azadirachtin can stop the crane fly infestation at the source: the soil. Leatherjackets, or crane fly larvae, live in the soil and feed on the roots of grass, crops, and other plants. By eating the roots, leatherjackets are capable of killing plants from the ground up.


Insecticidal soap (potassium salts of fatty acids) & pyrethrin combined are the organic equivalent of a 1-2 knock down punch. The soap will penetrate the insect's shell enough to weaken and dehydrate the insect and allow the pyrethrin to absorb into the insect to do its job.

Pyrethrin is a powerful nerve agent and will paralyze and kill the insect on contact. Keep in mind, this soap is not like dish detergent; it's a base from a blend of natural plant sources and pyrethrin oils and comes from the chrysanthemum flower. This product is an effective and organic combination that is sure to be the perfect crane fly control.

Azadirachtin, also known as clarified neem oil, is a product of the neem tree. This natural insecticide works by suffocating insects over time and is compliant for use in organic gardening.


Insecticidal soap & pyrethrin should be applied as soon as crane flies are discovered. Spray it as a contact killer. Use in accordance with directions on the product label. Azadirachtin or neem oil can be applied directly to your lawn and should be used at the first sign of grub damage. Use according to the product label.

Safer® Brand offers a variety of crane fly control products to help control and eliminate this lawn pest and revive your turfgrass. Please check out our crane fly control products for more details about how they work and how, when, where they should be applied.

If you are concerned about a plant or unsure of how it will react to these organic insecticide solutions, test an inconspicuous area of the plant and wait 24 hours before applying full coverage. As a general rule, much like watering, do not use any liquid insecticides in the peak of the day or when temperatures exceed 90°F.

Why Choose a Natural Solution?

Natural solutions break down quickly to their natural elements. They are preferable to chemical pesticides that leave residuals where they are sprayed, causing long-term detrimental effects on the environment.


Natural Predators


Natural predators of the crane fly include birds, skunks, and other grub-eating animals. Unfortunately, some of these predators may also do damage to the lawn or golf course, so it may not be a favorable solution to controlling European crane flies.


Birds, skunks and other grub-eating animals will dig into the ground to find the grubs. In digging, they can cause unsightly holes in the turf.


Birds usually eat grubs during the daytime, but skunks and other grub-eaters come out at night to dig for dinner.


Environmental Controls


European crane flies, like other crane flies, appear to favor moist environments. So, keeping the ground from being too moist, fixing areas with poor drainage, and avoiding irrigation at specific times in the life cycle of the European crane fly may be helpful in controlling this insect pest.

Removing some of the crane fly larvae may also help control an infestation.


Do not water between the time the eggs are laid and the time in which the first crane fly larva develops. Repair areas that have poor drainage around your yard and home.

At night, go out into the yard and rake up the larvae.


Do not water between the time the eggs are laid and the time in which the first instar (the developmental stage) larva develops. Repair poor drainage spots, particularly those with standing water, as soon as you see the moisture or water pooling in small areas on the ground.

Larvae come out at night and will be easier to find when it is dark.

Safer® Brand brings you a variety of effective insect control products that are gentler on the environment! Most of them proudly display the OMRI Listed® organic seal and are compliant for use in organic gardening!