Life cycle Adults come out of hibernation in spring and females lay their eggs in new grapevine stems in which larvae, and later pupae develop. There is one generation per year. Damage description Females empty out a small cavity in the new canes in which they lay an egg and then block the opening with frass. They then pierce a series of little holes girdling the stem just beneath the oviposition site and a second ring is pierced approximately 10-15 cm above this point. The tip of the stem will break at top girdle and fall off while the remaining portion of the infested stem will dry and eventually fall as well.
Damage has no effect on fruit production unless clusters are close to the injured portion.
Foliar galls approx. 4 mm in diameter, protruding from the ventral side of a leaf. Life cycle Complex. Two forms of this species develop on grapevine. Females may also produce young asexually, through parthenogenesis.