Invasive Crane Flies

in the Northeast

There are several species of native and non-injurious crane flies in NY that inhabit grassy habitats and can be found emerging from turfgrass.  Like many of them, T. paludosa and T. oleracea adults resemble oversized mosquitoes, but they do not feed and are weak (T. paludosa) to modest (T. oleracea) fliers.  One diagnostic character of European crane fly adults is a narrow dark-colored band along the leading edge of the wing adjacent to a light-colored band.  Unlike some native species, there are no pigmented areas or patterns on the veins, cross-veins or rest of the wing.  Adults of the two species can be differentiated in terms of relative length of wing to abdomen (in females), number of antennal segments and spacing between the eyes.  A definitive identification, however, will depend on a specialist.

Adults are 2.5-3.0 cm long, pupae 3.0-3.5 cm, mature larvae 3-4 cm and eggs 1.0 x 0.5 mm.  They complete one (T. paludosa) or two (T. oleracea) generations a year, with the emergence of adults occurring over a period of a few to several weeks at any one site, over the period of early spring (T. oleracea) and late July to September (both species).  Adult females will emerge, mate and lay most of their eggs all within the first day (T. paludosa) or 3-4 days (T. oleracea) of their brief reproductive lives, either in a single batch because gravid females are unable to fly any distance (T. paludosa) or in several batches because gravid females are more capable fliers (T. oleracea).  Each will deposit up to 200-300 black eggs at or near the soil surface.  Eggs are sensitive to drought and require wet conditions to survive, hatching in 1 (T. oleracea) or 1.5-2 (T. paludosa) weeks.

Larvae develop through four instars before they pupate.  Like eggs, development and survival is favored under moist conditions.  Active larvae mostly inhabit the top 3 cm of the soil where they feed on root hairs, roots and crowns of grass hosts.  Larger larvae may emerge to forage on stems and grass blades on the soil surface.  Larvae usually achieve third (T. paludosa) or fourth (T. oleracea) instar by the time cold temperatures force them to overwinter.  For T. paludosa, most damage is attributed to the rapidly growing fourth instars in the spring.  By mid-June, they have achieved their maximum size and move 3-5 cm deep in the soil where they remain in a non-feeding and inactive stage until pupation, which ends when pupae wriggle to the surface so the adult fly can emerge.  In contrast, T. oleracea does not have a long aestivation stage, leading to an adult emergence in spring, and the emergence of a second generation in the fall.  The empty pupal cases (exuviae or the “jackets” of the leatherjackets) look like small grey-black twigs protruding from the sward where they can be spotted on low-mown turf such as fairways, putting greens and tee boxes.

See comparison

See lifecycle

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*Tipula paludosa

*Tipula oleracea