Bostrichidae

Bostrichids are 3-6 mm long, and reddish-brown to black. They have a tuberculate and rasplike pronotum, and the body is truncate posteriorly. The head is directed down and not visible from above, the thorax is large and gives the adult a humpbacked appearance. Larvae are curved, the head is greatly reduced and the thorax enlarged. These beetles are distributed in the tropics and subtropics; many species in the family feed on wood, while others attack grain in storage. They feed in the sapwood of hardwoods, but a few attack softwoods. Larvae of some species attack freshly cut and partially seasoned wood with bark on the surface; others infest seasoned wood. Trees attacked include hickory, persimmon, and pecan, oak, beech, elm, and chestnut. Stored-food infestation is limited to a few species. Grain-feeding habits of these beetles may have been acquired recently, after the development of production agriculture and the practice of storing large quantities of grain. The large mandibles of bostrichids enable them to attack grain and structural wood. Oil seeds are not usually attacked.

Females bore circular, 2-3-mm-diameter entry holes through the bark into the sapwood; then they construct an egg tunnel across the grain. Eggs are laid at intervals in the tunnel and developing larvae feed in the sapwood. Larval feeding tunnels contain powdery frass. Feeding continues until the wood is dry. Adults can emerge after the wood has been processed into furniture or other items. Female bamboo borers deposit eggs in natural divisions and breaks in the wood, often at cut ends. Bostrichids usually have one generation per year, but the larvae take up to 6 years to develop in seasoned wood. Mating for some species is confined to the area immediately around the emergence hole. Males of Bostrychus capucinus, Het-erobostrychus brunneus, and Bostrychoplites cylincricus approach the female backwards after first drumming on the wood surface with their front legs. This mating strategy makes it possible to copulate in the narrow tunnels below the wood surface.

Large auger beetle, Bostrychopisjesuita Adults are 8-10 mm long, dark brown, and the body is rounded. The prothoraxhas a patch ofsetae anteriorly; the posterior margins ofthe forewings are rounded and without lobes. Emergence holes are about

5 mm diameter. This species is distributed in Australia where it attacks hardwoods, including eucalyptus.

Bamboo powderpost beetle, ghoon borer, Dinoderus minutus (Fig. 5.3b, e) Adults are 2.5-3.5 mm long, brown and cylindrical. Eggs are laid on the surface or in crevices, and hatching occurs in 3-7 days. Larval development takes about 6 weeks and the pupal period lasts about 8 days. Adults remain in the pupal chamber for 2-3 days before chewing through the wood to the surface. Severity of the infestation is associated with the starch content of the food material. Bamboo with less than 18% moisture contentis usually notattacked; smoke-dried bamboo is usually not attacked, because heating reduces the moisture content to about 5%. Larvae also feed in drugs, spices, cacao, maize, rice, stored grain, dried food, and flour. This species is native to Asia but it occurs in bamboo products around the world. Several other Dinoderus species attack dried cassava, bamboo, and wooden structures in Asia.

Oriental bostrichid, oriental wood borer, Heterobostrychus aequalis (Fig. 5.3d, f) Adults are 10-15 mm long, reddish brown to black and shiny. The pronotum is strongly convex and on the anterior half there are five or six broad, toothlike, marginal projections. Elytra are nearly tubular in shape; in males they end in two hook-like projections. Full-grown larvae are 6-13 mm long and yellowish white. Exit holes are about 3 mm diameter, and the frass is a fine powder. Eggs are laid on rough surfaces oflumber, logs, or in cracks or holes made by the female; hatching is in about 7 days. Larvae feed in 38-cm-long and 6-mm-diameter tunnels in the wood. Larval development takes 120-150 days; the pupal period is about 14 days. The life cycle can be completed in 1 year, but it can extend to

6 years. This large bostrichid is distributed in Asia, and occurs in Malaysia, Solomon Islands, New Caledonia, and Madagascar. It infests the sapwood of commercial woods, including Alstonia spp. (Pulai), Anisoptera spp. (Mersawa), Artocarpus spp. (Terap), Dillenia spp. (Simpoh), Gluta spp. (Rengas), Hevea brasiliensis (Rubberwood), Intsia palembanica (Merbau), Mangifera spp. (Machang), Myristica spp. (Penarah), and Shorea spp. (YellowMeranti, Yellow Seraya).

Bostrichidae Larvae
Figure 5.3 Coleoptera: Bostrichidae. (a) Prostephanus truncatus; (b) Dinoderus minutus; (c) Rhyzopertha dominica; (d) Heterobostrychus aequalis; (e) D. minutus larva; (f) H. aequalis larva; (g) P. truncatus larva; (h) R. dominica larva.

Boxwood borer, Heterobostrychus brunneus Adults are 6-13 mm long, black, and there are fine setae covering the body. Full-grown larvae are about 7 mm long and pale yellow. Exit holes in the wood surface are 3-6 mm diameter. The life cycle is completed inaboutiyear, butcan extend to 3 years. This species is common in Africa where it is often a pest in debarked logs and in timber used in floors and roof construction.

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