INSECTS

Woodworm or common furniture beetle

Order – Coleoptera
Family – Anobiidae
Species – Anobium punctatum

Appearance
Colour varies according to age from light reddish yellow through dark chocolate brown to pitchy-red. The elytra (wing case) show a series of longitudinal rows of dark-coloured marks on each.

Habits
Generally, the adult insects cause little damage and it is the larvae which cause damage which may range from one emergence hole in an artifact to the complete destruction of roof beams. Infestations will survive in cool, damp conditions but do not thrive in very dry conditions and humidities below 50% will prevent serious damage.

Diet
Anobium larvae will attack most wood except sound heart wood but they prefer softwood, non-tropical hardwoods and animal glue plywood. They will even develop in books when the pages are compressed, which is why the larvae are sometimes called bookworms. Books with wooden boards or compressed text-blocks provide a healthy diet for woodworm as the larvae have special yeast cells in their gut wall, which break down cellulose to digestible sugars and provide the larvae with the necessary supplement of vitamins.

Damage
Books stored on woodworm-infested wooden shelves can have eggs laid on them resulting in a complete life cycle being passed within the book.

Reproduction
The female of the adult beetle begins the cycle by laying a batch of up to 80 eggs (0.35–50 mm in length) in cracks and crevices on the surfaces of the timber, frequently the open end grain of sawn timber, that she has chosen as the home for her offspring. The eggs are whitish and acorn-shaped are often laid in groups of two to four.

After two to four weeks the eggs hatch into tiny grubs (larvae) which eat their way into the timber, where they will stay for two or three years, eating and growing, at the same time creating tunnels through the wood, generally along the line of the grain. The gallery or tunnel is made entirely by mandibles of the larva. Larva may grow to 7 mm. Except for the head the skin is soft and varies in colour from creamy-white through greyish-white to yellow. This goes on unnoticed from the outside surface of the timber, but, when the grubs reach maturity they turn towards an outer surface and then go through a metamorphosis change constructing a pupation chamber just below the surface. The length of the pupal stage is between six and eight weeks.

After pupation, the new adult emerges by biting the cap off this chamber, leaving the typical 'woodworm' or 'flight' hole of about 2-3mm diameter. Emergence of the beetles usually takes place during the months of May to August, but this period may be extended in centrally heated property. As soon as the pupae become beetles, their prime objective is to procreate as they only live for a few weeks.

The insect emerging is a small beetle, between 3 and 5 mm in length. As they fly away, wood dust and larval excreta (frass) may fall out of the hole leaving a characteristic sign of active beetle infestation – small piles of fresh dust

Control
Regularly check bindings with wooden boards. If major infestations are discovered which have severely damaged wooden structures then the University Surveyors or outside contractors will need to be consulted. However, check first with the University entymologist at the University Museum of Natural History.