An interesting and uncommon pest of apples was found recently in Douglas and Stearns counties. The apple curculio, Anthonomus quadrigibbus, a type of weevil, is related to plum curculio which is a common pest of apples. These two weevils are similar in size (about 1/4 inch long) and both have four bumps on their backs. However an apple curculio is reddish brown and has a longer and more slender snout while a plum curculio is darker colored with a shorter, stockier snout.
The apple curculio overwinters as an adult in debris on the ground. It moves to apples in the spring and damages developing apples by making small punctures as it feeds and oviposits. This damage can also cause the apple to become lumpy and misshapen. The oviposition punctures, unlike plum curculio, are small and round and not crescent-shaped. The larvae do not survive in developing apples; they can only finish their life cycle when the fruit drops prematurely. Apple curculio also develops on crabapple, juneberry (Amelanchier), and hawthorn.
Currently there are no management tactics for this insect. It is also not clear how widespread this insect is or how abundant it may become in an orchard. This has always been an uncommon insect that people did not need to worry about. However, if that is going to change, it would be good to know. It would be helpful to learn more about where this insect has been found in Minnesota and the amount of damage it is causing. If you discover this insect and its damage, please contact the author with information about its location.
Originally published in Yard and Garden Line News 2007