Europe, Asia
Poison hemlock (Conium maculatum)
Eggs are pale yellow and cylindrical. Early instar larvae are predominantly yellow with black head capsules. Later instars are light green with three dark green longitudinal stripes. Mature larvae can be up to 12 mm long. Pupal cases are reddish-brown. Adults are approximately 10 mm long with 18 mm wingspans. Adults are speckled brownish-gray and have a distinctive dark brown spot on each wing.
Adults emerge in early spring and begin mating and ovipositing. Eggs are deposited on the undersides of poison hemlock leaves. Hatching larvae feed on leaves, creating tubes of leaf particles. Leaf tubes are quickly abandoned when larvae are disturbed and drop to the ground. Larvae develop through five instars; late instars incorporate flower tissue into their tubes. They pupate in the soil with new adults emerging in midsummer. Adults overwinter in soil and plant litter. There is one generation per year.
Larval feeding defoliates plants which can lead to reduced reproduction and sometimes plant death. Many plants recover and produce more foliage after larvae have pupated.
Randall, C.B., J.E. Andreas, and J. Milan. 2024. Poison Hemlock Biocontrol Agents: History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2024-22-POISON HEMLOCK-A. https://bugwoodcloud.org/resource/files/31429.pdf