View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by University of Missouri: MOspace Insects and Diseases AGRICULTURAL MU Guide PUBLISHED BY UNIVERSITY EXTENSION, UNIVERSITY OF MISSOURI-COLUMBIA ArchiveHousehold-Invading Beetles Darryl P. Sanders Department of Entomology extension.missouri.eduSeveral species of beetles may invade homes. during summer and fall and Because they rarely damage anything in the home, are most likely to enter they generally are considered to be nuisance pests. homes during this time of These insects vary widely in size and habits. This year. publication describes some of the more common Foreign grain beetles household-invading beetles found in Missouri. show a strong attraction to houses, mobile homes, recre- Longhorned beetles ational vehicles, and even As the name suggests, longhorned beetles (family trailers when these structures are Cerambycidae) have long antennae, along with rela- new. Their attraction is believed version a tively long and slender bodies varying in length from to be due to minute mold that 0.4 to 1.5 inches, depending on the species (Figure 1). is often present in new build- In their growing stages, longhorned beetles are grub- ings. The adult beetle appar- like larvae that develop inside solid wood and are ently feeds on this mold. known as roundheaded wood borers. Eggs are laid by However, once inside, they may the adult female beetles on the bark of an appropriate be found feeding on a variety tree or log. of products such as grain These beetles do not enter homes on their own, and cereal products, ground but are carried into the house as larvae inside wood, nuts and seeds, dried fruits, usually firewood. Larvae in unused firewood will herbs and spices. In most develop into adults in late winter to early summer. cases, they are found in large b These new adult longhorned beetles then emerge numbers only when the inside the home and typically fly to the light of win- feeding material is-- damp and dows trying to get outside. Their presence may cause moldy. consternation, but longhorned beetles will not dam- Because of their mobility age anything in the house, nor will they lay eggs on and small size, no effectiveSee any wood in the house. or practical means exists for The best control method for longhorned beetles is controlling foreign grain bee- to pick them up and return them to the outdoors. tles as they enter buildings. In Removing unused firewood from the home in early new structures, they tend to spring also prevents their presence. Spraying fire- disappear in late fall and wood before bringing it into the house is not advis- early winter because of c able. No pesticide labels are approved for this prac- indoor heating and corre- Figure 1. (a, b, c) Long- tice, and the chemical probably would not penetrate sponding drying. This prob- horned beetles. deeply enough into the wood to reach the larvae. ably eliminates the mold Longhorned beetles are unique and fascinating they feed upon. insects, and they pose no threat to humans or wood Flying beetles may be killed with a in the home. household aerosol spray containing pyrethrins or pyrethroid-type insecti- Foreign grain beetle cides. Stored dry food products should The foreign grain beetle, Ahasverus advena, is a be kept in insect-proof containers and tiny reddish-brown beetle about 2 millimeters long safeguarded from mold. Aside from (Figure 2). It is strongly attracted to lights at night the nuisance caused by their presence, and is so small that it can readily pass through win- the foreign grain beetle is generally Figure 2. Foreign dow screening. These beetles are prevalent outdoors harmless. grain beetle. $.50 G 7368 Printed with soy ink on recycled paper Ground beetles Weevils enter by crawling through cracks or openings Ground beetles belong to the family Carabidae, around foundations, doors and windows. They can- one of the largest beetle families (Figure 3). The adults not fly. Indoors, they do no damage and are pests vary in length from about 0.1 inch to more than 1 only by their presence. inch. They are usually dark colored, Four species of house-invading weevils are com- often shiny and somewhat flattened. mon in Missouri. The imported longhorned weevil, They tend to be most active at night, Calomycterus setarius, is about 0.2 inch long and gray with some species highly attracted to colored due to a covering of tiny gray scales. Its larval lights. During the day they are stage develops in grass roots and other plants in found under objects on the grassy areas. The adults may feed upon the foliage of ground. They are fast runners and many plants. Even though they cannot fly, the adult it is common to see them moving weevil is attracted to lights at night and then may quickly along the ground. invade the house. Indoors, they tend to seek The strawberry root weevil, Otiorhynchus ovatus, hiding places under boxes or is brown to black and about 0.25 inch long. Its larval other objects on the floor, par- Figure 3. Ground beetle. stage develops in the roots of strawberries, raspber- ticularly in moist places such as ries, blueberries, grapes, many ornamental plants, basements. They invade houses more often in the fall clover, and even grasses. The adults may do slight when nighttime temperatures become cooler. The lar- damage to leaves of the same plants. val stages occur outdoors in the same surroundings The black vine weevil, Otiorhynchus sulcatus, is as adults, but adults and larvae are not necessarily very similar but slightly larger (about 0.4 inch long) found together. Both adults and larvae feed primarily and has small patches of yellowish setae (bristles) in on other insects. Because they are predators, they the black wing cover. It has approximately the same should be considered beneficial. range of host plants as the strawberry root weevil. When ground beetles enter homes, it is an acci- The Asiatic oak weevil, Cyrtepistomus castaneus, is dental invasion. They cannot survive and reproduce about 0.25 to 0.3 inch long and greenish-gray in color. there. The larval stage is a root feeder, while the adults Control measures indoors usually are not neces- attack the leaves. They attack many species of woody sary except to hand-pick or vacuum the beetles and plants but seem to prefer oak and chestnut. They are return them outdoors. Removing rocks, boards or attracted to houses during the fall, presumably in other objects that ground beetles may hide under search of hibernation quarters. from around outside walls discourages beetle accu- Caulked cracks and snug-fitting doors and win- mulation near the home. Caulking cracks and making dows prevent weevils from entering homes. Weevils, sure that doors and basement windows fit snugly also especially the strawberry root weevil, are strongly helps prevent entry. attracted to water and can be trapped in shallow pans To help prevent ground beetles from entering of water placed around building foundations. homes, spray 2 to 3 feet of the foundation from the Physical removal is best with a vacuum sweeper. ground up, and treat a band around the house from Chemical control usually is not necessary. If popula- the foundation out about 5 to 10 feet. For these pur- tions are very large, a barrier spray around the home poses, use a spray of 0.5 percent diazinon or 0.5 per- with either chlorpyrifos or diazinon, as described cent chlorpyrifos (Dursban®). above, will help. Weevils Multicolored Asian lady beetle Weevils are beetles of the family Curculionidae The multicolored Asian lady beetle, Harmonia (Figure 4). They are characterized by a snout and a axyridis, like several other species of lady beetles, is pair of elbowed antennae attached to considered beneficial because both the growing stage the sides of the snout. They often larvae and the adult beetles eat aphids and other soft- “play dead” when disturbed. Some bodied insects. The multicolored Asian lady beetle species of weevils may migrate into feeds on its prey in forests, orchards, alfalfa and other homes in the summer and fall. field crops, home gardens and urban environments. The grublike larvae feed on a In other words, wherever there is a food source, this wide variety of outdoor plants, par- beetle will probably be found. ticularly ornamentals. After the In the fall, these lady beetles converge to hiber- grubs pupate and become adults, they nate. In Japan they do this in crevices on the sides of are often attracted indoors. Cool cliffs, huddled together by the thousands. In nighttime temperatures may be Missouri, they often invade houses in great numbers the reason for the invasion. Figure 4. Strawberry to hibernate. root weevil. Page 2 G 7368 The adult multicolored Asian lady beetle is about harm humans or pets but are pests only by their pres- one-quarter inch long and oval shaped, about two- ence inside the home. During the spring, they will thirds as wide as it is long. The general color is yellow leave their hibernation sites. This may be the time to yellowish orange. The wing covers that form a when the greatest numbers will be seen in houses. domelike shell over most of the body may have as Since lady beetles are beneficial, it is best to try to many as 19 black spots or none, or any number in keep them out of the house so they do not become between (see Figure 5). In addition, markings on the pests. To prevent home invasion, all cracks and white pronotum, the small area between the head and crevices should be caulked.