There are hundreds of large crane fly species in North America, belonging to the Tipulidae family. They are sometimes referred to as daddy-long-legs, mosquito hawks or water spiders. They have a variety of habitats, from moist woodlands to grassy or aquatic areas, depending on the species. Most are not considered pests of home turf, golf courses, gardens, crops or pastures. There are however two problematic species in North America, booth native to Europe, who are responsible for causing extensive damage, especially to turf grasses. The first one, commonly known as the European Crane Fly (Tipula paludosa) it is most commonly found in British Columbia, Ontario, Quebec, and in the states of New York, Oregon and Washington. The second species is known as the Common Crane Fly (Tipula oleracea). It is most commonly found in British Columbia, California, Michigan and New York State.
General Appearance of Crane Flies
Crane flies are long, gangly looking, two winged flies that look like giant mosquitos. They are however completely harmless and they neither bite nor sting. The adults measure about 2-3 cm in length (roughly 3/4″ to just over 1″), with the males being slightly smaller than the females. They are light brown to grayish in colour with long slender bodies, 6 long legs, and one pair of wings with distinctive venation and snout-like mouthparts. They have up to 19 segments on their antennas that can be used to help identify the exact species. The females of the species have pointed ovipositors at the tip of their abdomen, used to deposit their eggs. While the tips of male abdomens are blunt, with claspers located under the abdomen that are used to hold the female while mating. Females also have thicker abdomens. Crane flies have a distinctive V-shaped groove located behind their head on the thorax. They undergo complete metamorphosis with the adults only living long enough to mate and lay eggs. They are also known for being poor fliers.
General Appearance of Leather Jackets
The larvae of crane flies are called leather jackets, named for their tough leathery outer skin, which is light grey to brown in colour. They look like short, fat, brownish worms, but when stretched out from their usual contracted state they can measure approximately 4cm (1 1/2″) long.
European Crane Fly (Tipula paludosa)
European Crane Fly (Tipula paludosa) are attracted to moist habitats, especially turf grass and other grassy areas, including pastures and cereal crops. In urban areas the adults tend to congregate on the sides of buildings and window screens. They are particularly bad fliers and tend to lay their eggs near where they emerged from the soil. Their wings have a narrow, dark-colored band that runs along the outer edge of their wings the remainder of the wing being translucent. A distinguishing trait are their antennas that have 14 segments (Common Crane Fly (Tipula oleracea) have 13. European crane flies emerge from the soil, after sunset, typically in September. They begin mating and laying their eggs within 24 hours of their emergence. The impregnated females then deposit approximately 300 eggs into the upper soil level 1/2″) and die shortly after. The eggs which are oval and black in colour require moisture and a temperature of at least 14 degrees Celsius in order to hatch. Under these ideal conditions they will hatch within 2 weeks. They have one generation per year.
The larvae, called leatherjackets, begin feeding in the fall, soon after hatching. They use their rasping mouthparts to feed on plant roots, rhizomes and foliage. They pass through a total of 4 instar stages that have voracious appetites and can cause extensive damage to turf and pasture grasses causing yellowing, thinning, and large bare patches. Affected turf pulls up easily and secondary pests like skunks and racoons further damage the turf by digging for the leather jackets. Damage is similar to grub damage except the leather jackets do not destroy all of the roots as grubs do. Leather jackets over winter in the soil as 3rd instars, then continue their feeding frenzy in the spring. In milder winters they can continue to feed through some or part of the winter. (Note: Although leatherjackets over winter many do not survive the winter especially if they are exposed to cold, dry conditions.) This spring feeding frenzy is the most damaging and lasts until early summer (late May to mid-June) when they cease feeding, move down into the upper soil profile (3-5 cm deep) and remain in a non-feeding stage until pupation. Pupation occurs from late August through early-to-mid-September, when the pupae wriggle to the top of the soil in the late night to early morning and the adults emerge (omafra (2013)).
Common Crane Fly (Tipula oleracea)
Common Crane Fly (Tipula oleracea) are very similar to European Crane Fly (Tipula paludosa). They are usually greyish or occasionally a rust colour, often with a dark stripe that runs down the top center of the abdomen and/or dark lateral stripes. A distinguishing trait are their antennas that have 13 segments. They differ from the European crane fly mainly in that they have 2 generations per year. “Overwintering larvae from the previous fall pupate in February-March and emerge as adults in late March-April. Mating takes place and eggs are laid. The second generation of larvae mature from April through September and adults emerge for the second generation at the same time as the one generation European from August through September” (Nutri Lawn (n.d.)). The wings on the common crane fly are longer than European craneflies, being longer than their body, this enables them to fly a little farther than the European craneflies. Damage can be more extensive due to having 2 generations and a longer feeding period.
Managing European and Common Crane flies
- Maintain good lawn care practices to keep the turf as healthy and vigorous as possible so it can better withstand an attack.
- Keep the lawns on the drier side at egg laying time.
- Improve drainage. Since crane flies are attracted to moist habitats make sure your soil is draining freely.
- Encourage birds to visit your yard. They love to feed on the leather jackets and do a decent job controlling populations.
- Monitor your lawns regularly for signs of leather jacket damage.
- Hand picking, raking or vacuuming up the leather jackets is an option if your populations are low. They reside in the upper surface of the soil by day but on damp evenings and cloudy days they come to the surface to feed on the leaf blades. That is the best time to gather them up.
- Tarps can be laid over the turf, after a heavy watering, then removed after the leather jackets have come up to the top.
Beneficial nematodes (Steinernema feltiae)
Are a safe, natural way to provide some control to leatherjacket populations. Researchers have found them to be about 55% effective (Oregon State University (n.d.)). These microscopic, parasitic, non-segmented worms, (which occur naturally in soil all over the world), seek out the leatherjackets and attack the pest by entering natural body openings or by penetration of the body wall. Once inside, they release a bacterium that kills the host within 48 hours. The nematodes then continue to reproduce inside the dead pest and release a new generation of hungry nematodes, which set off in search of further prey. Nematodes are not harmful to birds, animals, people or plant life.
The best time to apply these specific nematodes is in spring when the soil temperature is above 12ºC (54ºF) and in the fall as soon as the eggs begin to hatch. Apply to moist lawns and keep continuously moist for about 2 weeks. You can find nematodes at larger garden nurseries in the refrigerated section or by mail order. Read the label carefully for storage, application and specific hosts it is effective against.
Chemical Control for Homeowners
For regions permitted the use of chemicals Visit Pacific Northwest Extension Publication, ‘Turfgrass-Crane fly’ for a list of chemical controls available. Be sure to check with your region first to see what is lawful for you to use.
Photo Credits: photos by the Author.
Updated Nov. 18, 2022
CABI, (n.d.). Tipula paludosa (European crane fly). https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.54013
Ministry of Agriculture, Food and Rural Affairs, (2022). European crane fly. https://www.ontario.ca/page/european-crane-fly
MISSOURI DEPARTMENT OF CONSERVATION, (n.d.). Large Crane Flies. https://mdc.mo.gov/discover-nature/field-guide/large-crane-flies
Nutri Lawn (n.d.), https://www.nutrilawn.com/leather-jackets
OMAFRA (2013), ‘European Crane Fly’, Retrieved on Jan.17, 2021 from: http://www.omafra.gov.on.ca/english/crops/facts/13-023.htm
Oregon State University (n.d.), A Pacific Northwest Extension Publication, ‘Turfgrass-Crane fly’. https://pnwhandbooks.org/insect/hort/turfgrass/turfgrass-crane-fly
Peck D. C., (2006). European crane fly. https://ecommons.cornell.edu/bitstream/handle/1813/42421/european-crane-fly-FS-NYSIPM.pdf?
Site One Landscape Supply (n.d.). Leatherjacket. https://www.siteone.ca/home/resources-services/technical-support/leatherjacket.aspx
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