Crane Fly, Leatherjackets

Class: Diptera
Order: Tipulidae
Family: Tipula paludosa and T. oleracea

Identification: I was going to hold off on these guys for the pest of the month but I’m seeing way too many bouncing off my porch light to let them go unnoted. In case you have not heard, we now have two pestiferous species of crane flies in our area, all thanks to our European allies. Both species look very similar if not identical. Adult crane flies resemble a huge mosquito with very long delicate legs. The front edge of the wing consists of a smoky gray-brown band; the body is colored in the same gray to light tan fashion. Crane fly heads are elongated and form a snout; this is a distinguishing feature of species in the genus, Tipula. Separating the two species of Tipula is difficult. T. oleracea is generally bigger than the European crane fly. Females of T. oleracea have wings that extend to or past the tip of the abdomen. Both sexes will show a difference in the placement of the eyes, when you get good at seeing this character, you can ‘eyeball’ the different species in the field. T. oleracea eye’s are very close together (almost touching at the bottom of the eye) while T. paludosa (European crane fly) has a notable distance between the two eyes. Larvae are brownish, leathery grubs. Larvae of these two species are, as of yet, indistinguishable.

Life History: One way to tell the different species is through the phenology. T. oleracea has two generations a year, so if you see crane flies flying in the early spring, these are T. oleracea. In fact, I even saw some flying as early as January this year. Typically, T. oleracea adults have peak activity during March-April (the first generation) and in September (the second generation). T. paludosa has one generation and flies during September. You will see adults bouncing around, depositing eggs on your lawn right now. Eggs will hatch and larvae will begin feeding on the roots and blades of your lawn. T. oleracea also can feed on vegetables too! Once mature, larvae will go inactive to develop and pupate in the soil, and finally emerging as adults to start the next generation.

Damage: Crane flies can be very abundant and are probably responsible for the most pesticides (by weight) applied in home yards in our county. However, your lawn can tolerate a large population of crane flies. WSU has traditionally recommended treatment at 25-50 larvae/ft2. Damage depends on: your lawn’s health, drainage, fertilization programs, and age. Newly laid sod and newly established turf tends to suffer more from crane fly feeding than established, healthy lawns. Healthy lawns can have 40 larvae/ft2 (maybe more) with out showing any signs of damage. Larvae feed on roots of many turf types. Larvae also (this is a bazaar sight) crawl up leaf blades and even your garden herbs and vegetables to eat foliage; keep in mind that these have no legs! Most of this feeding occurs at night.

Control: Please keep yourself educated about crane fly control. Multiple factors are contributing to the current gray area of crane fly management. First, we don’t know much about the new species. Secondly, we will experience a dramatic change in the chemical tools that are normally used to control crane flies. Finally, we may be close to finding a reasonably effective natural control for crane flies.

Cultural management practices are best for managing crane flies. Did you know crane flies are from a huge fly family and most species are aquatic to semi-aquatic organisms? Don’t lay turf in soggy areas, you will have crane fly problems (among others like moss). Most turf grasses do best with direct sunlight. Maintaining lawns in sunny areas of the yard will also lessen the impact of crane fly damage. Root health and growth is very important for promoting healthy turf and deterring crane fly damage. Remove thatch when the thatch layer exceeds ½ inch in thickness. Aerate your lawn to reduce compaction and increase drainage in the soil; this will provide a better habitat for your lawn’s root system. Aeration only needs to be done every 2-4 years depending on the your soil type and the degree of compaction. Good fertilization practices are another important factor for reducing crane fly problems. Provide enough fertilization to promote root growth but be aware of your soil type and your lawn’s requirements. Also be sensitive to water issues in your neighborhood; some fertilization practices may contribute to water quality problems. Finally do your best to irrigate properly. Irrigation practices should be done to promote deep root growth. Remember, healthy lawns can tolerate large crane fly populations.

Biological control potentials have not been intensively explored here in the Pacific Northwest. However, beneficial nematode producers have been receptive to our cries for effective beneficial nematodes. We are currently working with a few species of nematodes to use for crane fly biological control in Whatcom County. I’d like your help in finding good crane fly populations to treat with nematodes this fall and next spring. Please call if you don’t mind me poking and prodding your turf! Other controls for crane fly are already out there eating your leatherjackets. Probably the most significant predators of crane fly are birds, mainly starlings and robins. Our own Al McHenry swears that robins have quit their seasonal migration to stick around and fill up on crane flies all winter long! Other good predators that you might not want to hear about are yellow jackets; late season yellow jackets are voracious against the large leatherjackets that you find in late summer. Finally, ground beetles are extremely good at foraging for leatherjackets. These beetles are very susceptible to pesticides and take awhile to re-colonize your lawn after they have been zapped.

Pesticide use for crane fly control has changed significantly since the introduction of the European crane fly. WSU has not recommended the use of diazinon for quite some time. Diazinon applied to lawns will irritate larvae and draw them towards the surface. This leaves them quite exposed to bird predation. Through accumulation, birds that feed on these leatherjackets can receive a lethal dose of diazinon. This problem of bird-kills prompted the use of Dursban (chlorpyrifos) for crane fly control. Chlorpyrifos is very effective for controlling crane fly problems. However, after revising a risk assessment, the EPA has called for a cancellation of chlorpyrifos products for home use (among others) by next year. So Master Gardener’s, this will make your job a little tougher when the flood of crane fly calls come in. Next year, you will have to discuss other options for crane fly control with your clients and diazinon should not be the only option discussed.

Cane fly management, IPM-style, will most likely result in the DO NOTHING strategy. I like this one the best. I have a healthy lawn, with great drainage and well-developed roots. I also know that my crane fly population was not a threat to my lawn. How do I know this? I monitor my crane fly population. A good time to do this is in winter and early spring. Larvae are large and easy to see by February but the earlier, the better. Select at least 4 areas of your lawn to sample. Cut a square that is 6”x6”. Leatherjackets will usually be right there as the soil separates form the fine root hairs (about 1-2 inches deep). Some larvae may be in the thatch too, so you may have to break apart the clump of grass. Count the number of larvae present and multiply this by 4 for each soil sample. This gives you the estimated number of larvae per square foot. You can replace your sample and the grass will establish again. These samples will tell you your crane fly density, your potential for a problem, and where in your yard you have populations. If some of your samples are high, treat that area of your yard. You do not have to treat the areas that do not have problems, this is a waste of money and wasteful pesticide usage. A watchful eye will take you a long way in successful in crane fly management.

For more information on Cranefly go to WSU, EPA & WSDA's Cranefly Webpage.