Early in the spring, the adult cane maggot (Pegomya rubivora), which resembles a little housefly, arrives and lays eggs in the tips of shoots.
The larvae (maggots) burrow approximately 15 centimetres (6 inches) deep into the pit, then turn outward and girdle the shoot in 4-6 days.
Above the encircled region, the top of the shoot wilts and dies. Although the damage is comparable to that caused by the cane borer, it occurs sooner, and there is no evident exterior girdling.
The larva continues to bore into the pith until it reaches the plant’s base, where it pupates and overwinters.
Host plants: red raspberry, blackcap, loganberry, and occasionally blackberry
Territory: Throughout the United States
Damage caused by Raspberry Cane Maggot:
Raspberry canes may be affected during the winter in any of the following ways: snow breakdown, tip dieback and top kill. Snow breakage happens when snow presses on or on the canes, causing them to break. The easiest way to maintain control is to adjust or remove the impediments (such as hedges) that allow the snow to drift around the canes. Defer the heading back operation until the spring in locations where tip dieback and top kill occur year after year, and chop off the dead parts of the canes in the process.
Life history and Habits:
The insect spends the winter in the soil as a pupa. In April, the adult flies emerge. The female lays her eggs towards the young canes’ crowns. The baby maggots burrow into the pith of new shoots and tunnel downward after hatching. Feeding, later on, entails girdling the cane slightly beneath the bark.
