Crane flies have earned a somewhat false reputation due to their resemblance to the deadliest of all insects, the mosquito. In many areas, these flies are regarded as pests and provoke the notion that mosquitoes are growing larger each year. Nothing could be further from the truth! These gentle insects are simply a sign of either early spring or late summer. The adult flies have nothing but the thought of mating on their minds.
Unfortunately, due to their mosquito or spider-like appearance, they are commonly referred to as daddy longlegs or mosquito hawks. These misunderstood insects belong to the largest family of flies, Tipulidae, which falls under the order Diptera (true flies). Charles Paul Alexander, an entomologist that specialized in flies, thoroughly described thousands of crane flies and their larvae in his publications. There are now around 15,000 known species of these medium to large-sized flies.
Tipulidae are highly diverse and are present in all continents, except for Antarctica. Though crane flies and their larvae are generally beneficial to a wide array of ecosystem types (freshwater systems, pasturelands, steppes, etc.), some have earned pest status due to their consumption of economically important crops. Notable species include Tipula paludosa and Tipula oleracea, which are common in both the US and Europe.
What Do Crane Flies & Crane Fly Larvae Look Like?
Adult crane flies have long legs that bend along two junctions and resemble stilts. Coupled with their narrow bodies and slender wings, their features look like those of mammoth-sized mosquitoes. Their appendages are extremely delicate as they can easily come off of the main body. Depending on the species, elongated wing features are slightly variable and the wingspan can reach a length of 4 inches (10 cm). An adult grows to just 1 – 2 inches (2.5 – 5 cm) on average.
In terms of color, adult crane flies can be either brown, yellow, orange, or grey. They may have unique patterns on the dorsal regions of their bodies, and their pair of wings may be unpigmented, striped, or spotted. Antennae are highly segmented (up to 19 segments) and extend from junctures adjacent to their large eyes. Their rostrums may be short to notably long and usually terminate in a point called the nasus.
In contrast, crane fly larvae have relatively simple, cylindrical bodies that taper on both ends. In this sense, they are similar to worms. They are clearly segmented and have distinct head, abdominal, and terminal regions. The head is equipped with mandibles and mouthparts that are made for chewing. The larvae have remarkably tough skin, which is why they are commonly referred to as leatherjackets. They vary in color (grey, white, brown, green) and may have specks along the length of their bodies. Some species produce larvae with fairly translucent integuments (outer layer).
Crane Fly & Crane Fly Larvae Habitats – Where Do They Live?
Some crane flies have a knack for occurring in all sorts of places, as long as a water source is nearby. They favor freshwater or semi-aquatic ecosystems that have flourishing communities of flora. Damp soil and high amounts of decaying matter are a plus. The understory and floor in wetland forests can foster large communities of larvae and adult crane flies. The larvae favor humus-rich mud (or even fungi or dung) that surrounds leaf litter and putrefying organic material. Some also like the cushions or mats made by mosses or aquatic plants.
Several Tipula species can thrive in dry soils as long as sources of nutrition are present. This diversity of habitats explains why crane flies can be found just about everywhere, with some species potentially becoming invasive. The larvae tend to be more problematic in large numbers as adult crane flies have such short lifespans and don’t eat. Keep an eye out for them during the first few days of spring as there may be some searching for mates close to your garden’s water features.
In some areas, these gentle flies and their larvae have occurred in numbers that are large enough to wreak havoc on the local ecosystem. The larvae may destroy large amounts of turfgrass, particularly during rainy seasons and on rich, regularly moistened substrates. Manual and chemical means of control may have to be used in case of infestation.
What Do Crane Flies & Crane Fly Larvae Eat? (Crane Fly Diet)
Adult crane flies don’t usually eat anything. They rely on the energy stores that they accumulated earlier in their life cycle. They may occasionally feed on nectar, though they focus most of their efforts on mating instead of eating. Contrary to reports that may be found online, crane fly adults aren’t actually capable of biting or stinging.
Crane fly larvae, on the other hand, seem to have enduring appetites. Depending on the species, the larvae can be detritivores that feed on decaying plant matter, herbivores that feed on roots and vegetables, or even carnivores and insectivores that feed on other larvae and small insects. Herbivorous larvae that feed on the root systems of crops and grasses are particularly problematic in some areas. Their feeding habits can result in stunted crop growth or in bald patches of grass in golf courses and cricket grounds.
The Life Cycle of Crane Flies
The crane fly life cycle is similar to that of other flies that have lengthy larval stages and remarkably short adult phases. They start off as eggs laid on the surface of algal mats, wet soils, water bodies, or dry soils. Most Tipulidae eggs are black in color and are equipped with a filament for attachment or anchoring purposes. These eggs may be dropped from a height or laid directly onto the substrate. This stage of the life cycle lasts for 1 – 2 weeks, after which the eggs hatch into larvae.
Larvae spend most of their time eating and accumulating the necessary nutrients for developing into their more complex adult forms. The larval stage lasts for several months to years and includes a few stages of growth, each separated by a molting phase. These stages are formally termed instars. Once the larvae enter the final instar, they may leave their habitats in search of a secure area for pupation.
The pupal stage can last for a few weeks to months, during which the developing crane flies are protected by their tough cases. Crane fly pupae are normally found close to the soil surface or under leaf litter. The adult crane flies of some species emerge as early as spring, whereas some emerge closer to mid or late summer. The adult flies then search for mates and will soon lay hundreds of eggs, starting the life cycle once more.
How to Attract Crane Flies to Ponds
Most adult crane flies are naturally attracted to bodies of water as they prefer to lay their eggs in moist areas or on the water’s surface. If potential predators are largely absent, chances are your pond system or its surrounding vegetation and substrate have already been home to a few crane flies. If you’d like to enlarge your crane fly population or are interested in attracting some new species, you can try placing a few night lights around your pond. These will surely attract crane flies, just as they would a host of many other insects.
To increase your pond system’s chances of sustaining generations of crane flies, you can deliberately place leaf litter or decaying wood along its edges. This should encourage larvae to feed around the pond and pupate there as well. Do keep in mind that this may, unfortunately, attract other insects and larger pests. Moreover, if your pond’s surroundings are covered in lawn or turf, you may wish to avoid attracting this type of insect.
Are Crane Flies & Crane Fly Larvae Beneficial?
While large amounts of crane flies can be problematic, controlled populations are highly beneficial to naturalized pond systems. Larvae aid in hastening the decomposition process of damaged plants, wood, and organic waste. The movement of larvae in the soil can open up air pockets that increase aerobic microbial activity and fend off potentially harmful pathogens.
The adults are harmless and can serve as prey, along with the rest of the life stages, to many fish, birds, and small mammals. Their presence can help diversify your pond or garden as they can aid in maintaining a balanced food web and sustain the needs of larger predators. Lastly, the short-lived adults can help pollinate your pond edge and marginal plants through spring and summer. These are undoubtedly beneficial insects that have simply been misunderstood due to their mosquito-like appearance.
