Old House Borer (Hylotrupes bajulus)

The Old House Borer belongs to the beetle family Cerambycidae, a group also known as the "long horned" beetles.   The key-identifying characteristic of this family is long, thin antennae that are often as long (or longer) than the body of the beetle.  The beetle's body has a slightly flattened appearance. Its colour may appear dark grey, but is usually brownish black to black.  The prothorax (behind the head) is rounded in shape and contains two raised, shiny black "bumps."  The wing covers of the old house borer are black, with lighter grey coloured areas forming bands that are usually present about one-half down the wing covers.  Yellowish-grey hairs may be present on the head and the prothorax.

Old house borers attack softwoods (pine, fir and spruce) only, commonly used in building construction. But they can also be found below and in the bark of oak, beech and other hard woods logs and firewood. Adults emerge from infested wood from May and continue into June or even July, depending on a climate conditions. The body length of the adult old house borer males is 1.2 - 3.5 mm, and the females 2.8 - 4.6. Lifetime of adults is typically a few weeks, but may vary from 1 - 4 weeks depending on the ecological conditions.

Soon after mating the female deposits several batches of eggs in softwood cracks.  Female can extent the ovipositor up to 35 mm and allows egg laying in cracks more than 42 mm deep. The eggs pass down the ovipositor in 3.3 to 11 seconds. The number of eggs laid per female varies about 170. It depends on the size of the Hylotrupes larva. Hylotrupes bajulus is sensitive to geomagnetic field. When reduce horizontal component of geomagnetic field, development and egg production increased. An area with an enlarged horizontal component of geomagnetic field decreases egg production. Parthenogenesis produces males. The ratio of females to males was 9:1, but may vary.

The eggs hatch in about 23 days at 28°C average, but at lower temperature it takes longer. New larvae immediately bore into the softwood wood for 2-7 years typically but with ease conditions larvae could stays in the wood much longer, till 19 years maximum (about 0.2% of population). The full-grown larva (200–500 mg) tunnels to the surface of the wood and cuts an oval hole (known as exit hole), which is 0,6 cm to 1,2 cm in diameter. Exit hole is sometimes sealed with packed frass. Just below this exit hole is a pupation chamber where the larva pupate.  The pupation stage is initiated by a cool period and lasts 3-6 weeks. After that period the pupa slough to a beetle, so life cycle of the old house borer has been completed.