Beetles belonging to the genus Otiorhynchus in the family Curculionidae are all weevil species, many of which are “root weevil” pests that damage cultivated plants on residential and commercial properties. Root weevils are well known among gardeners and landscape architects for their habit of feeding on a variety of ornamental and agricultural plants, such as strawberry, raspberry, clover, spruce, Douglas-fir and many woody shrubs. In addition to damaging plants, several root weevil species in Massachusetts are among the most common of all “incidental,” or “occasional” home-invading insect pest species in the state. The weevil species that invade Massachusetts homes most frequently during the warmer months include strawberry root weevils (O. ovatus), rough strawberry root weevils (O. rugostriatus), and black vine weevils (O. sulcatus).
While root weevil species vary in body size, color, and exterior bodily patterns, virtually all root weevil species are very similar in appearance. Of the three root weevil pests mentioned above, the black root weevil species is the largest with a ½ inch long dark-colored body that is covered in tiny hairs that appear as conspicuous yellow polka dots. Reddish-brown strawberry root weevils are around ¼ of an inch in length, while the nearly identical rough strawberry root weevil is slightly smaller at ⅓ of an inch in length. Root weevils can also be identified by their peculiar habit of falling to the ground when they feel threatened or disturbed, and although these pests have wings, they are unable to fly. Adult root weevils feed on foliage at night, and females deposit eggs in moist soil near plant roots in order to provide their developing larval offspring with food upon hatching. Larvae, or “grubs” reach adulthood in June or later in the summer season, and their limbless maggot-like bodies are short, white, and ribbed.
Adults frequently enter homes during the midsummer and fall in Massachusetts, and invasions are particularly common during bouts of excessively hot and/or dry bouts of weather. It is not quite accurate to call root weevils incidental invaders, as researchers believe that the pests are lured into homes by indoor moisture sources. While root weevils will not damage property or inflict injury to humans or pets, large indoor populations often pose a tremendous nuisance. Root weevils sometimes hitchhike indoors on potted plants, and occasionally, adults seek indoor shelter from dropping temperatures during the fall season. Indoor insecticide applications are not recommended for root weevils due to their habit of dispersing throughout homes. However, extensive infestations can usually be eliminated with Pyrethroid insecticides.
Have you ever encountered root weevils in your home?