Invasive Crane Flies

in the Northeast

Control tactics should be directed against the larvae because adults are hard to target and short-lived.  Suggested thresholds range from 15 to 50 larvae per sq. ft, depending on overall turf health.  In Ontario, Canada, lawns have been reported with as many as 75-125 larvae/sq. ft.  Even if thresholds are surpassed, it is important to keep in mind that leatherjackets can suffer very high mortality due to predation by birds and other vertebrates.  Vigorous home lawns and golf courses can therefore support relatively high populations.

Because of their sensitivity to dry conditions, careful management of soil moisture levels may be a key cultural control tactic to reduce populations.  Some strategies are to carefully manipulate the timing and frequency of irrigation, particularly during the oviposition period, to better drain chronically infested areas, and to allow the sward to dry (i.e. avoiding irrigation) in the fall.  Other recommendations to alleviate problems are to maintain a vigorous stand that is more tolerant to infestation and to rake up larvae at night when they emerge to feed at the soil surface.  Another possibility is to soak the green, cover with a tarpaulin, and dispose of larvae trapped underneath after they moved to the surface to escape the excess moisture.

If necessary, preventive applications of insecticides are best made in the late fall (September to October) at the time of egg laying or when larvae are smaller and still active at the soil surface.  Otherwise curative applications can be made in spring (May) once high populations or feeding damage of T. paludosa are detected.  If populations of T. oleracea are present, a late fall treatment would be superior, as it would target both species; T. oleracea completes two generations a year and susceptible larval populations are hard to target in the spring.  There are many control products registered for leatherjacket control in turfgrass of NY (LINK: Cornell Pest Management Guidelines for Commercial Turfgrass).  Results from efficacy trials in NY state against T. paludosa indicate that imidacloprid and trichlorfon offer 73-87% control in either the spring or fall window.  Carbaryl, chlorpyrifos and one biological control option (Beauveria bassiana, an entomopathogenic fungus) are other alternatives labeled for leatherjackets in NYS that have shown more variable, but positive, results.  The entomopathogenic nematode, Steinernema carpocapsae, is a biological alternative that has been promoted in the Northwest.