The common name “mosquito hawk” evokes the image of a beneficial insect relentlessly hunting down the blood-feeding pests that plague summer evenings. This nickname, along with “skeeter eater,” is frequently applied to the crane fly, a large, gangly insect that often blunders into homes. Its imposing appearance leads many to believe it is a helpful predator. This widespread assumption raises the question: is the crane fly truly an ally in mosquito control, or is it merely a harmless, misunderstood visitor?
Unmasking the “Mosquito Hawk”
The insect most commonly labeled a “mosquito hawk” or “skeeter eater” is the crane fly, belonging to the family Tipulidae. These insects are often mistaken for giant mosquitoes because of their slender bodies and disproportionately long, fragile legs. Their size, which can reach up to 1.5 inches in length with a substantial wingspan, makes them appear intimidating.
Adult crane flies possess a distinctive, slow, and clumsy flight pattern, often resulting in them losing their legs easily. A notable feature is the V-shaped suture located on the back of the thorax, which helps distinguish them from other large flies. The name “mosquito hawk” is entirely a misnomer that has persisted despite the insect’s true nature.
What Crane Flies Actually Eat
The adult crane fly is not a predator and does not consume mosquitoes at any point in its life cycle. Many species of adult crane flies do not feed at all, dedicating their brief lifespans solely to reproduction. If they do feed, it is typically a light consumption of dew or flower nectar, as they lack the mouthparts necessary for biting or preying on other insects.
The larval stage, often referred to as leatherjackets due to their tough, leathery skin, does the majority of the feeding. These larvae live in moist soil and primarily function as detritivores, consuming decaying organic matter like dead leaves and wood. By breaking down this material, they play a beneficial role in decomposition and nutrient cycling. Although some aquatic larvae may occasionally prey on other small invertebrates, they do not specifically target mosquito larvae.
Are Crane Flies Pests?
While the adult crane fly is harmless to humans and plants, the feeding habits of the leatherjackets can shift them from beneficial decomposers to agricultural pests. Larvae of certain species, notably the European crane fly (Tipula paludosa), can cause damage to lawns and turfgrass. These larvae overwinter in the soil and become active feeders on the roots and crowns of grass plants during the spring and fall.
A high population of leatherjackets can result in dead, brown patches in a lawn, resembling damage caused by grubs. The larvae feed just below the soil surface, sometimes pulling grass blades down into their burrows. The presence of large numbers of larvae can also lead to secondary damage from other animals. Predators such as skunks, raccoons, and birds will dig and probe the turf in search of the leatherjackets, tearing up the lawn.
Real Mosquito Predators
The actual “hawks” of the insect world are a diverse group of genuine predators. Dragonflies and damselflies, which are sometimes included in the general term “mosquito hawk,” are highly effective hunters. Adult dragonflies catch and consume adult mosquitoes in mid-air, utilizing their powerful flight and large eyes.
The aquatic larvae of dragonflies and damselflies are also voracious predators, feeding on mosquito larvae in the water where mosquitoes breed. Fish are another significant predator, especially species like the mosquitofish (Gambusia affinis), which is frequently introduced into ponds and water troughs for biological control. Furthermore, the larvae of some non-biting mosquito species, such as those in the genus Toxorhynchites, are known to prey exclusively on the larvae of other mosquitoes.