Plum Curculio
Conotrachelus nenuphar
Host Plants:
On Crops: Plums, peaches, apples and many other fruit trees
Where Found:
Most of North America
Description:
Small, brown mottled snout beetles up to one-fourth inch (6mm) long with humps on their rounded backs, and distinctive long beaks, or snouts. Overwintering adults emerge quite suddenly in mid-spring, when mid-season apples are in bloom. They find their way to blossoms and immature fruits, which they eat as they find mates. Females then lay eggs in fruits, and cut a crescent-shaped expansion scar in the fruit so the larvae will have room to grow. Fruits that look like they have been pierced with a fingernail have been visited by curculios.
Damage:
The growing larvae may not last long in apples, because expanding apples push so hard on the larvae that they cannot feed. Plum curculio larvae have much more success in plums, peaches and other softer fruits. Curculio feeding and egg-laying sites often become starting points for fungal diseases.
Preventing Problems:
Growing a diversity of plants and maintaining habitat for birds can keep populations from getting out of control. Allowing poultry to forage under fruit trees can suppress plum curculios, too.
Managing Outbreaks:
At about the time apples drop their petals, go out in the cool of the morning, spread sheets beneath fruit trees, and shake all the limbs you can to dislodge curculios. Collected specimens can be drowned in a pail of soapy water.
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