Author: Eric R. Day, Manager, Insect Identification Lab, Virginia Tech
Publication Number 444-278, Revised December 2005
Order: Lepidoptera
Family: Sesiidae
Species: Podosesia syringae (Harris)
Size: The moth is about 1 inch long with a wingspan of 1 1/2 inches.
Color: The fore wings are brown or chocolate color and the hind wings are clear with a dark border. The larvae are pure white worms with brown heads.
Description: The adult has clear wings and is wasp-like in appearance.
Habitat: Both lilac and ash are known hosts.
Life Cycle: As winter passes, the immature larvae is in the stem of lilac and ash near the surface of the soil. Feeding and continued development begins in early spring and is completed by early summer. It then pupates in the stems and in three weeks emerges as the adult (early May through early July). Oviposition occurs shortly after emergence and mating. The eggs are laid about the base of lilac canes or on ash stems. The hatching larvae bore into the host and become half grown by cold weather. There is one generation per year.
Description of Damage: The base of infested branches becomes swollen and the bark cracks and breaks away from the wood. Canes suddenly wilt and show fine sawdust-like borings exuding from holes in the bark. Plants may be completely destroyed if the pest is not controlled.
Remarks: A closely related borer on ash is called the banded ash clearwing. It is similar to the ash borer, but emerges in August. The timing for control is for late summer applications of insecticides.An introduced pest, the emerald ash borer, has been discovered in several states, including Michigan and Ohio. If you suspect that you have this pest and you are a resident of Virginia, please submit a sample to the Virginia Tech Insect Identification Lab through your local Extension office.
Chemical: Completely cover the main trunk by spraying with an insecticide labeled for borer control in early May and again in about six weeks often provides good control.
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