Crane flies, often mistakenly called "mosquito hawks" or "giant mosquitoes," are a common sight around the world. These gangly insects, with their long legs and delicate wings, frequently cause confusion and concern. Despite their resemblance to oversized mosquitoes, crane flies are generally harmless and play a vital role in the ecosystem. This article delves into the life cycle, diet, and ecological significance of these fascinating creatures, debunking common misconceptions along the way.
Identifying Crane Flies: More Than Just Giant Mosquitoes
Crane flies belong to the family Tipulidae, boasting over 15,000 species worldwide. While they share the order Diptera (true flies) with mosquitoes, significant differences set them apart. Crane flies typically range in size from 1/16 inch to 1-1/2 inches long, with some species, like the giant western crane fly (Holorusia hespera), reaching up to 1.4 inches (35 millimeters) in length. Their wingspan can extend up to 3 inches.
Key characteristics of crane flies include:
- Slender bodies and long, fragile legs that easily break off.
- Narrow, membranous wings, often with a wingspan of 1.25 to 2 inches (31 to 50 millimeters).
- Dull colors, such as brown, black, or pale yellow.
- A distinct 'V'-shaped suture on their thorax near the wing bases.
The tip of a female crane fly's abdomen is pointy, while the tip of the male crane fly's abdomen is blunt.
Debunking the Myths: What Crane Flies Don't Do
One of the most prevalent misconceptions is that crane flies prey on mosquitoes, hence the nickname "mosquito hawk" or "skeeter eater". However, this is false. Crane flies lack the piercing, sucking mouthparts of mosquitoes and do not feed on blood. In fact, many adult crane flies have no functional mouthparts at all.
Read also: Mosquito Feeding Habits
Another common myth is that crane flies are dangerous. They don't bite or sting and pose no threat to humans. While their large size might be unsettling to some, they are generally harmless houseguests.
Furthermore, crane flies are sometimes confused with "daddy longlegs". The name "daddy longlegs" is also commonly used for arachnids of the family Pholcidae and the order Opiliones.
Life Cycle: From Leatherjackets to Fragile Flyers
Crane flies undergo a complete metamorphosis with four distinct life stages: egg, larva, pupa, and adult.
- Egg: Female crane flies lay small, black eggs in moist ground, often near water sources or in over-watered lawns. These eggs hatch within 6 to 14 days.
- Larva: The larvae, often called "leatherjackets" due to their tough, brown skin, resemble worms. They live in the soil or aquatic environments, feeding on decaying organic matter, algae, and sometimes the roots of plants. As they grow, larvae molt several times, shedding their old skin. The crane fly larva eats the roots of vegetation and other plants until it reaches adulthood. Leatherjackets live in the soil underneath grass and turf where they feed on the roots. The larval stage is the most extended, lasting weeks or months depending on the species and environment.
- Pupa: After the final molt, the larva transforms into a pupa. This stage takes place in the soil and is the transition phase between the larva and adult fly. Pupae often have wing sheaths and prominent eyes and may be covered in spines. During this stage, the body undergoes metamorphosis into the adult form. The pupal stage typically lasts for 5 to 12 days, although some species may remain in this stage for a few months.
- Adult: The adult crane fly emerges from the pupal case with a focus on reproduction. Most species have short adult life spans, ranging from 10 to 15 days. Some adults do not eat at all and don’t even have mouths. Those that do eat only drink nectar from flowers. The tip of a female cranefly's abdomen is pointy. The tip of the male crane fly's abdomen is blunt.
The entire life cycle, from egg to death, can be as short as six weeks, although some species, particularly in arctic climates, may live up to five years.
Diet: What Crane Flies Really Eat
The diet of crane flies varies depending on their life stage. Adult crane flies rarely feed, but whenever they feed, they often eat nectar and pollen. However, crane flies do not actually need to feed on anything during their adult stage.
Read also: Galapagos Hawk Feeding Habits
Crane fly larvae are voracious eaters. Crane fly larvae are often a problem for many farmers around the world. Crane fly larvae feed primarily on decomposing organic matter. Some species are reported to feed on roots of forage crops, turf grasses and seedling field crops.
Habitat: Where Crane Flies Thrive
Crane flies are found worldwide, inhabiting a variety of environments. They commonly occur in moist environments such as woodlands, streams and flood plains although some species inhabit open fields, dry rangeland and even desert environments.
Larval habitats include all kinds of freshwater, semiaquatic environments. Some Tipuloidea, including Dolichopeza, are found in moist to wet cushions of mosses or liverworts. Ctenophora species are found in decaying wood or sodden logs. Nephrotoma and Tipula larvae are found in dry soils of pasturelands, lawns, and steppe.
Ecological Role: More Than Just a Nuisance
Despite their potential to be agricultural pests, crane flies play a vital role in the ecosystem.
- Decomposers: Crane fly larvae help break down decaying organic matter, contributing to nutrient cycling in soil and aquatic environments.
- Food Source: Crane flies are valuable food items for bats, birds, lizards, spiders, and predatory insects. Skunks and other animals may damage lawns while digging for crane fly larvae which are called "leatherjackets".
- Pollinators: Some adult crane flies feed on nectar and pollen, acting as pollinators for various plant species.
Crane Flies as Pests: A Concern for Agriculture
While generally harmless, certain crane fly species can pose a threat to agriculture. The larvae of some species feed on the roots of crops, turf grasses, and seedling field crops, potentially stunting growth or killing plants. Tipula paludosa and T. oleracea have become invasive in the United States. The larvae have been observed on many crops, including vegetables, fruits, cereals, pasture, lawn grasses, and ornamental plants.
Read also: The Hoxsey Diet
Control Measures: Minimizing Their Impact
Controlling crane fly populations can be challenging, especially since they are often present in large numbers. However, several strategies can help minimize their impact:
- Maintain a Healthy Lawn: Proper lawn care practices, such as aeration and fertilization, can promote strong root growth, making grasses more resistant to larval feeding.
- Manage Moisture: Reduce overwatering and improve drainage to create less favorable conditions for egg-laying and larval development.
- Biological Control: Encourage natural predators like birds and beneficial insects to help regulate crane fly populations.
- Insecticides: In severe cases, insecticides may be used to control larval infestations. However, this should be a last resort, as insecticides can harm beneficial insects and other wildlife.
Crane Flies Around Your Home: Prevention and Removal
While crane flies don’t bite, they can be a nuisance if they get into your house, especially as they hover around the lights.
The best thing you can do is keep your windows and doors closed to prevent them from getting inside. If a crane fly does end up in your house, you’ll probably be able to cup it in your hands to let it outside. Crane flies are harmless and focus on conserving energy for mating, so releasing one outside is often easy.