Apple Flea Weevils
What Are Apple Flea Weevils?
Apple Flea Weevils (Rhynchaenus pallicornis) are small, dull, snout beetles and have nothing to do with fleas. Apple flea weevils are pests of economic importance. Orchards with the worst affected trees were found in unmanaged orchards or orchards managed using organic practices.
The adult weevils are highly mobile and can fly between host plants. Weevils overwinter beneath or close to the host plants and emerge as budburst occurs.
As much as 60% of leaves were affected by the weevils with less activity noted on leaves close to the trunk.
Apple Flea Weevils Life Cycle
The weevils initially feed on the buds and newly developing leaves of apple trees in the spring, then when the leaves are about two-thirds grown, the weevils begin laying eggs along the leaves midribs.
The apple flea weevil larvae then feed by burrowing or mining their way through the leaf, between its layers to its margins, where they pupate before finally emerging as adult weevils in May and June.
There is just one generation per year, so newly emerged weevils quickly begin feeding for a few weeks before going into torpor until the following spring.
As the leaves mature they can appear blistered and have small holes like that of birdshot through them. The yellow-brown larvae of the apple flea weevil can cause significant damage to the expected yield.
Damage resulted in a corresponding yield loss if the weevils were not controlled. Yield loss exceeding 90% in some organically managed orchards has made producers keen to find effective means of control.
Other tree species under attack by this nuisance garden pest include hazelnut, elm, hawthorn, cherry and crab apples.
How To Control Apple Flea Weevils
Sticky and pheromone traps have not proved to be effective in controlling this weevil and pesticides do work but make organic control obsolete.
The alternatives researchers have been looking at concern the role that hymenopteran parasites could play. Recent research showed several parasitic wasp species attacking larvae and this might also be true of the adults. Sticky traps were useful for surveillance sampling.