Blackheaded Ash Sawfly - Tethida barda (Say)
Brownheaded Ash Sawfly - Tomostehus multicinctus (Rohwer)
Spiny Ash Sawfly - Eupareophora parca (Cresson)
Solomon, J.D.; Leininger, T.D.; Wilson, A.D.; Anderson, R.L.; Thompson, L.C.; McCracken, F.I. 1993. Ash pests: A guide to major insects, diseases, air pollution injury and chemical injury. Gen. Tech. Rep. SO-96. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 45 p.
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Importance. - The ash sawflies are widely distributed throughout eastern North America and westward to the Great Plains. Young trees in new plantations and ornamental plantings seem particularly susceptible to defoliation.
Identifying the Insects. - Larvae of the blackheaded and brownheaded ash sawflies have greenish-to yellowish-white bodies. The spiny ash sawfly larvae have dark heads and gray bodies with numerous forked, dark spines. Larvae of all these species are about 16 to 19 mm long at maturity. Adults are typical sawflies, with mostly black bodies marked with red and white, and measure 6 to 8 mm in length.
Identifying the Injury. - The larvae feed gregariously in groups of 4 to 20, often lined up in rows feeding side by side. Young larvae chew holes in the leaflets, and older larvae eat entire leaflets. Heavily infested young trees may be completely defoliated in 1 to 2 weeks. Older trees may be so ragged that most of the leaves drop prematurely.
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Larva(e)
James Solomon, USDA Forest Service |
Larva(e)
James Solomon, USDA Forest Service |
Biology. - In the spring, adults lay eggs in slits cut along the outer margins of young leaflets. Larvae feed and mature in early to mid- May in the South, later in the North. When mature, they drop to the ground where they make earthen cocoons in the soil and spend the summer, fall, and winter. In the spring, larvae pupate and emerge as adults to begin the cycle again. There is one generation per year.
Control. - Natural enemies usually keep sawfly densities low. Insecticides are effective in young plantations and ornamental plantings when severe infestations occur.
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