Contarinia virginianae

Crops Affected: chokecherry and Saskatoon berry

Life Cycle:

• Adults are tiny flies (midges)
• Adults emerge from overwintered pupae in late spring (May) and begin to lay eggs in host flowers
• Eggs hatch to produce distinctive bright orange larvae (maggots)
  • There will be many maggots in one space
  • Maggots feed within the developing fruit
• Feeding causes the fruit to become enlarged and discoloured (creating a swollen gall) and the developing seeds abort
• Larvae feed inside the gall until late July and then exit to drop to the ground to pupate
• The hollow fruit will drop off the plant before the berries are fully ripe
• There is one generation per season

Symptoms:

• Infected fruit become a swollen and distorted gall, often pear-shaped
  • The galls are green initially, but will eventually turn bright red
  • Galls may be 4-5 times the size of normal, uninfected fruit
  • Galls are hollow and will contain many small, orange maggots in the cavity
• The galls will stand out from the normal fruit that surround them
• The number of infected fruit can range from one in hundreds of fruit to severe infestations where almost all of the fruit are infected

Monitoring:

• Watch plants for gall development

Management:

• Remove and destroy infected galls when they are detected, prior to larvae exiting the fruit
  • This may reduce survival and keep populations from increasing
• No registered insecticides are available

Opening the gall reveals a hollow cavity full of bright orange maggots