The Relationship of Lygus Bugs and Thrips to Fruit Deformity in Strawberries

Abstract

Lygus bugs, Lygus hesperus Knight, caged on the flowers and fruit of strawberries were found to cause fruit deformity or “Catfacing.” Deformity is caused by bugs feeding on individual achenes rather than by a toxic action on the reccptacle itself. Lygus bugs feed on large and small achenes. Consequently, when fruit deformity is caused by lygus bugs, at least some of the achenes in the depressed areas are enlarged. Poor pollination likewise causes “catfacing,” but in such instances all of the achenes in the depressed areas are small. Thrips, Frankliniella occidentalis (Pergande), do not seem to cause fruit deformity. Their feeding sometimes causes a withering of the smaller flowers, but such blossoms usually do not produce marketable fruit. Moderate populations of thrips cause a limited amount of discoloration of the berries, particularly to the seeds, and the fruit under the calyx, but such damage does not seem to warrant control measures. However, very high populations may feed over the entire surface of developing berries and cause a golden brown discoloration that makes the fruit unmarketable.