Pest description and crop damage A slender species of sawfly that is about 6 to 12 mm long; females are slightly larger than the males. Both sexes have a black head and thorax. The male has a brownish yellow abdomen. The female abdomen is reddish orange and the posterior half is black. Larvae are straw-yellow in color, with a slightly darker head. Sawflies are in the insect order Hymenoptera but their larvae resemble a lepidopteran caterpillar. Female stem girdlers cause substantial damage to new growth by their girdling habit when laying eggs (see below), severely reducing crop growth and fruit production. Larvae cause significant damage to plants when they bore into, and feed within, canes.
Biology and life history After feeding within canes throughout the summer, full-grown, dormant larvae overwinter in canes and pupate in early spring. After about two weeks as a pupa, the adult emerges, usually in early May. Females lay their eggs singly, inserting them into the pith of new shoots. After each egg is laid, the female walks up the shoot, about 0.5 to 1 inch, and girdles it with her saw-like ovipositor. Usually, a portion of the shoot remains uncut, and the almost severed, wilted tip may remain attached for some time. One female can lay up to 30 eggs and therefore girdle 30 shoots. Presumably, girdling is done to prevent shoot growth and possible damage to the egg or young larva.
Management-chemical control: HOME USE
No products are registered for control of this pest in home gardens.
Management-chemical control: COMMERCIAL USE
- fenpropathrin (Danitol 2.4EC) at 0.2 to 0.3 lb ai/A. PHI 3 days. Do not exceed 0.6 lb ai/A per season. Toxic to bees; do not use when bees are foraging. Also toxic to fish and other aquatic invertebrates.