Identifying Pests

Why do I need to know what bug it is?

When you are faced with an infested item or collection, it is important to identify what insect you are dealing with. Correctly identifying insects enables you to determine if the pest poses a problem to the collections and to choose the most appropriate treatment and control methods.

Primary Pests

These insects are those that represent the greatest risk to collections. The descriptions will help you to decide what you have found.


There are many species of carpet beetle. One of the most common is the varied carpet beetle, which has a round shape covered with a pattern of grey and gold scales and is typically about 2-3mm long. The larvae of carpet beetles (short, hairy caterpillar-like things) tend to feed on protein-based material such as silk, wool, fur, feathers and animal specimens.

Adult carpet beetles often find their way into buildings through windows, chimneys and roof spaces. You may notice an influx after the spring breeding season.


There are two main kinds of clothes moth. In both kinds, it is the larval form that does the most damage. The larvae of the clothes moth resemble small hairy caterpillars, and eat trails through collection material until they are ready to pupate into adults. The larvae tend to feed on protein-based material such as wool, silk and fur. They often prefer to feed on soiled or dirty areas of the object.

The larvae of the case-making moth form their “cocoons” from the material of the object on which they are feeding. This can make them very difficult to spot, as they blend into the object’s surface.

The larvae of the webbing clothes moth leave trails of webbing mixed with dirt and droppings behind them, which makes them a much “messier” infestation.

The adult moths of both species are small and grey-brown, and tend to “scuttle” rather than fly. They are about 5-7mm long. When at rest their wings are folded along their back.


Silverfish are long, silver-coloured insects that often graze on the surface of paper-based material. Silverfish can grow up to about 7mm in length. They especially like to feed on glues and adhesives. Silverfish prefer quite humid conditions, but may migrate from their damp breeding spaces into collection spaces.

Silverfish have a “nymph” stage rather than a larval stage – that is, the young silverfish just hatched from its egg looks exactly like an adult, only much smaller.


Booklice graze on microscopic moulds that grow on the surface of paper-based material, leaving surface damage similar to that caused by silverfish. They are also attracted to glues, binders and paper sizing.

Booklice are usually very tiny (less than 1mm in length) and are a slightly transparent brown colour. They do not have wings.


There are many species of borer beetles that infest wood, including furniture beetle, drugstore beetle and powderpost beetle. Species that affect collection material can be between 2-6mm long.

Borers chew through wood, paper and books and leave networks of tunnels with perfectly round exit holes. Borers can be difficult to detect – piles of fresh dust at the base of holes are one of the only ways to detect an active infestation. Borers may also affect building materials, display cases, storage cabinets and other furniture.


Termites are not commonly found in collections but can pose a serious problem to the building itself. Termites have also been found in large stacks of paper, and in various wooden objects. Outdoor sculpture may be at a higher risk of termite infestation.

Termites may actively consume collection material or the object may become damaged due to its proximity to the nest. Termites create very humid conditions, so mould may also become a problem.

There are three main types of termite: subterranean, drywood and dampwood. Subterranean termites usually cause most damage to buildings; drywood termites usually cause most damage to objects, unless subterranean termites have gained access to the item through the ground or floor.

Signs of damage can include changes in the appearance of a wooden surface, as material is being eaten away behind it. Subterranean termites will block up any holes in the wood with hard piles of dirt and wood particles, which are visible from the outside. This is done to maintain the temperature and humidity of the tunnels. Sometimes you can hear termites chewing.


These are often found in bird nests and museum collection and will feed on any general debris, including dead insects. The larvae are large and hairy and will bore holes in objects. The adults are 3-4mm long, hairy and superficially resemble spiders, but are generally slow-moving. Often only one will be found – this is not a serious problem.


These belong to the same family as the wood-boring beetles, but bore into hard, dried vegetable material such as biscuits, tobacco, nuts and dried plant specimens. They may also attack high-starch paper objects (eg papier-mâché) and freeze-dried animal specimens.

Adults are 2-3mm long, very active and will fly. Larvae are not very active and will concentrate their activities in one area, leaving neat exit holes in objects.


Hide and leather beetles may attack wool, fur, feathers and textiles but will also attack leathers and skins. The adults are larger than carpet beetles (6-10mm). Larvae are large and very hairy.

Secondary Pests

The pests listed below are usually no cause for panic, but should be prevented from living in or near your building.
They are commonly found in and around buildings but are not usually directly threatening to museum collections. Some, like cockroaches, have been known to feed on collection material, but more usually these pests stain or dirty objects or surfaces, and act as a food source for other insects – bugs love to eat other bugs!
The presence of these pests indicates that conditions in your building are suitable for insect growth and that alterations may be needed in your cleaning and maintenance procedures – for example, a healthy spider population indicates that you probably have healthy populations of other insects.

• Millipedes
• Centipedes
• Wasps
• Spiders
• Ants
• Cockroaches
• Birds
• Rodents
• Bats
• Crickets
• Large moths