You probably have seen an insect that looks like a mosquito but with much longer legs and a bigger body. But despite its looks and having many nicknames including mosquito hawk, mosquito eater, and daddy-long-legs, the real name of this insect is crane fly. And they don’t actually eat mosquitoes!
The nicknames mosquito eater and mosquito hawk probably exist because some crane fly larvae may feed on mosquito larvae, but this is rare. It is important to note that adult crane flies do not bite humans so, other than their annoying sound, they are harmless to both us and mosquitoes.
Crane flies are insects from the Tipulidae family which can be found everywhere from tropics to cold high-latitude environments. That is why these flies have different names all around the world.
For example, in the United Kingdom, they are commonly referred to as daddy-long-legs while in other places crane flies have acquired names like mosquito hawks, gallynippers, gollywhoppers, and, of course, mosquito eaters.
The adult crane fly has a very slender body with legs up to 4 inches in length (100 millimeters). As the build of these flies is not very proportional, they are not good fliers. In fact, they often wobble when they fly as well as fly in irregular patterns which makes them quite easy to catch.
Even though the most common names for crane flies paint them as mosquito hunters, adult crane flies do not prey on mosquitoes. Their main source of sustenance is flower nectar. They are actually physically incapable of killing and therefore eating mosquitoes.
Their larvae can, however, be harmful to plants. For this reason, they have acquired the status of an agricultural pest in many countries.
Crane-fly larvae often live in the very top layers of the soil and therefore eat the roots and sometimes even leaves of the plants that are growing in this soil. This can not only stunt plant growth but can even kill the plants altogether.
The life cycle of a crane fly
The female adult crane fly carries mature eggs around which, when fertilized by a male during mating, are deposited. This deposit usually happens in wet soil, but crane fly eggs have also been found in many other areas including dry soil and the surface of bodies of water.
There is no motherly care here. Unlike what is normal with vertebrates like birds and mammals, the mother just pushes the fertilized eggs out of her ovipositor and flies off.
The eggs will hatch within a week or two and the larvae then make their way towards any food source. It is at this larval stage of development that a crane fly can be destructive.
Crane fly larvae, which also go by the name of leatherjackets in some regions, are worm-like creatures. Some latch onto the roots or shoots of a plant, deriving their nutrients from that part of the plant. This affects the growth and the quantity of produce recovered from the plant.
In addition to vegetation and roots, leatherjackets also feed on decaying matter and wood, small aquatic insects, invertebrates, and any decaying plant life they may encounter. Which is why they often serve an important role as decomposers.
The thickness of the outer covering of the larvae of crane flies is responsible for their odd name: leatherjackets. Besides the nature of their covering, this stage of a crane fly’s life can be identified by its cylindrical shape with narrow ends, which is completely different from what is seen in mosquito larvae, which are found in bodies of water and look like tiny sticks with giant heads.
The leatherjackets’ feeding habit is similar to that of a mosquito: they feed at night and rest during the daytime. This might also be considered a defense mechanism against predators that abound during the day.
In northern and temperate latitudes, the larvae go into hibernation during the winter. Once the cold season ends, the larvae begin to feed.
In mid to late spring, they build themselves pupal cases in which they hide and undergo metamorphosis. Then, in late summer or early fall, the adult crane flies emerge from their cocoons and go off to play their own role in nature. Crane flies do not live very long. Adults only live for a few days!
However, since there are thousands of crane flies species, there are a few differences in the larval stage of development between species which are not focused on physical appearance but rather on location. While some larvae can adapt successfully to living on land, others find the water more conducive to their activities. These can be seen in swampy areas seeking potential food sources.
The ecological benefits of mosquito eaters
Although the larva of a crane fly is known to cause damage to plants, they actually provide some ecological benefits as well.
The biological activities of those species which live on land have been shown to improve the soil structure as well as to increase the soil’s organic matter content. The larvae of certain species of crane flies are capable of eating the larvae of other harmful insects including mosquitoes.
Some adult crane flies feed on nectar though others might not eat anything at all.
What they all have in common is that they all provide a source of food for other animals like amphibians, reptiles, birds, and some types of fish. This, in turn, provides some balance in the food chain and helps us to be sure that mosquito eaters are not simply useless insects that are flying around and annoying us.
So, there you have it: a little introduction to crane flies a.k.a. mosquito eaters.
Despite the fact that they actually do not eat mosquitoes (even though their larvae sometimes can), these flies are still pretty interesting creatures that are worth learning more about. It is only when we know more we can better understand the insects we encounter and differentiate them from mosquitoes and other pests so that we know not to harm them when we come across them.