''Acalitus essigi'', the redberry mite, is an

eriophyid Eriophyidae is a family of more than 200 genera of mites, which live as plant parasites, commonly causing galls or other damage to the plant tissues and hence known as gall mites. About 3,600 species have been described, but this is probably ...

mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...

which is a serious pest of commercially produced

blackberries The blackberry is an edible fruit produced by many species in the genus ''Rubus'' in the family Rosaceae, hybrids among these species within the subgenus ''Rubus'', and hybrids between the subgenera ''Rubus'' and ''Idaeobatus''. The taxonomy of ...

in the United States. The redberry mite is microscopic, requiring at least a 20× hand lens to detect. It has two pairs of legs and a thin, translucent appearance. Overwintering mites colonize tiny spaces beneath the exterior scales of dormant buds of blackberries. As the season progresses, redberry mite migration occurs up the flower stem to colonize leaf axial bracts, the fruit's calyx area as well as the spaces between berry druplets. Redberry mite feeding prevents berries from ripening uniformly, causing from one to many druplets to remain as a bright red cluster on the otherwise black and fully ripe fruit. Affected druplets never do ripen, causing the entire fruit to be inedible and unmarketable. Historically, redberry mite has been most damaging to blackberry varieties such as Chester, which mature later in the summer (August and September). Yield loss to redberry mite damage can range from 10 to 50% of the total blackberry crop. Infestations of redberry mite are often controlled with

lime sulfur In horticulture, lime sulfur (British spelling lime sulphur) is mainly a mixture of calcium polysulfides and thiosulfate (plus other reaction by-products as sulfite and sulfate) formed by reacting calcium hydroxide with elemental sulfur, used in p ...

or natural acaricidal oils.

External links

Redberry Mite IPM
Agricultural pest mites Eriophyidae Arachnids of North America Animals described in 1928 {{agriculture-stub