The term “mosquito hawk” is a colloquial name for the crane fly, a number of species of flies that exist in the family Tipulidae. Mosquito hawks are known for their size and impressive wingspan. They are often mistaken for large mosquitoes, but unlike mosquitoes, they do not bite humans or feed on blood.
In fact, crane flies completely lack functioning mandibles, so they could not bite even if they wanted to. Instead, they feed like other flies by using a proboscis to lap up organic material. As such, they are completely harmless to humans, only serving as minor household pests.
The family Tipulidae is one of the largest, consisting of 15,000 species of individual fly distributed over 525 genera and subgenera. Current classifications of crane flies owe their existence to the late U.S. entomologist Charles Paul Alexander (1889-1981), who almost single-handedly described and classified over 11,000 species of crane fly over the course of his illustrious career. Crane flies are found all over the world, though most individual species tend to stick to one biome.
Appearance/Anatomy Of The Mosquito Hawk
Adult crane flies resemble large mosquitos, hence the name mosquito hawk. Like all insects, crane fly bodies are composed of three parts: head, thorax, and abdomen. Attached to the abdomen are 6 deciduous legs that can easily be removed. The average wingspan is approximately 1-6 cm, though some species of crane fly can reach a wingspan up to 11cm. Because the term “crane fly” refers to a number of different species, there is substantial variation in size and appearance of individual species of crane fly.
According to Matthew Bertone Ph.D., an entomologist associated with North Carolina State University who specializes in flies, the smallest known species of crane fly could comfortably rest on the head of the largest known species. Their color can vary from orange to yellow to black, and they display a diverse array of patterns and body markings across species. Some species of crane fly lack wings entirely and resemble spiders in their morphology and behavior. Males typically have longer and more segmented antennae than females, though the specific reason for this difference is not known.
In addition to morphological differences between adult specimens, the larvae of different species show different characteristics. They are generally cylindrical in shape and taper towards the front end. Crane fly larvae are sometimes called “leatherjackets” and exhibit some pretty neat adaptations. Some species inflate their abdomen to move through the soil easier, some have fringed setae that they use to break water tension, and others have caterpillar-like forearms with hooks at the end used to grapple things and interact with the environment.
Behavior/Life-Cycle Of The Mosquito Hawk
Most species of crane fly have an average lifespan of only 10-15 days. Because of this short lifespan, crane flies eat very little, if they eat anything at all. Despite there being stories of them biting, crane flies completely lack functioning mandibles and cannot bite. Some species are observed to feed off of decaying organic material and other species have specialized mouthpieces for feeding on flower nectar. Crane flies have large and well-developed compound eyes, but it is unknown how much they rely on sight to get around their environment as opposed to other sense like chemoreception.
Given that its lifespan is so short, the majority of time in an adult crane fly’s life is spent looking for opportunities to mate and reproduce. Crane flies exhibit a number of different mating strategies and patterns. Some species will aggregate into all-male swarms which attract females. Some will just fly around with their legs outstretched, searching for female pheromones. In other species, groups of males and females will conglomerate in dark secluded areas to reproduce. Although their mating behavior is probably not more complex than other kinds of flies, the sheer variety of crane flies and species-specific adaptations means that there are still a lot of unanswered questions surrounding their mating practices.
Generally, as soon as copulation occurs, the female will lay her fertilized eggs, usually in wet soil or algae. Some will lay their eggs on the surface of a body of water and some simply drop their eggs midflight. Once they hatch, crane fly larvae feed on microflora, algae, or dead plant matter. Strangely, some species of crane fly larva are predatory and feed on aquatic invertebrates and insects, in contrast with there being no known predatory species of adult crane fly. Crane fly larvae can actually play an ecologically beneficial role as they break down decaying material and introduce beneficial microbes to the soil. They also serve as the base of the food chain for animals like birds, spiders, fish, amphibians, and reptiles.
Crane flies are classified as agricultural pests. Crane fly larvae feed on crops and unchecked crane fly populations can destroy entire yields of crops. European crane flies and marsh crane flies have recently been introduced to the United States as an invasive species and have been observed on a number of crops. Other species of crane fly can take up residence in houses, especially old houses that may have rotting wood in their foundations. Though they aren’t dangerous to humans, they can be destructive, as feeding off rotting wood in a house can further compromise the structural integrity of a house.
There is currently some scientific debate over the legitimacy of the phylogenetic family Tipulidae. Some argue that the taxon is polyphyletic; that is, it groups organisms together than do not share a common ancestor. They argue that Tipulidae should be split up in smaller families that better reflect the insects’ genetic ancestry. In most recent classifications, the grouping Pediciidae, which was previously considered a subfamily of Tipulidae, is now ranked as its own distinct family. There are also a handful of crane flies whose ancestry scientists are not sure of, like phantom craneflies, winter crane flies, and assorted primitive species of crane fly. Despite this disagreement on edge cases, it is generally accepted that the majority of crane fly species are classified correctly.