Species characteristics:
Liposcelis bostrychophilus (bostrychophila)Areas where found:
Most booklice species are found in natural habitats such as animal nests, tree trunk crevices, under bark (hence the alternative name of barklice) and on leaves. However, those species that have achieved pest status are widely distributed and often found in ware-houses, food manufacturing premises, granaries and museums
as well as domestic and retail premises. Here they will infest materials of plant and animal origin including stored food, plaster, leather, woodwork and even books.
Many species are cosmopolitan and their countries of origin are unknown. Different species exhibit different temperature requirements. Thus Lepinotus patruelis is frequently encountered in cool situations, e.g. warehouses, whilst Liposcelis bostrychophilus, which is thought to have originated from Africa, prefers warmer situations. In heated buildings continuously brooded species (e.g. Liposcelis spp.) will continue to breed throughout the year. Other species (e.g. Trogium spp.) produce only one generation per year and may overwinter as nymphs.
Lifecycle:
(Based on that of Liposcelis bostrychophilus) The females of some species of booklouse may reproduce without fertilisation, the males being suppressed, dwarf or entirely lacking. During her life each female produces some 200 eggs. They are usually laid separately at a rate of 1-3 per day and, being sticky, become covered with framents of food or rubbish or adhere to the substrate. The eggs of some outdoor species are however laid in batches and covered with a silken web. The smooth, pearl-coloured eggs hatch in 1-2 weeks. The emerging nymph closely resembles the adult and will pass through 3-8 moults depending on species (four in the case of L. bostrychophilus) to reach maturity in about 15 days. With each successive moult the nymph becomes progressively more like the adult as eyes, antennae and wings (if present) begin to develop. Ambient conditions and the quality of the diet profoundly influence the speed of psocid development. The life-cycle is usually completed
in one month, the adults surviving for up to 6 months. The insects are only moderately well adapted to the environments they inhabit. Their small size and flattened bodies mean that they can readily hide in cracks and crevices. They do, however, possess a relatively thin cuticle which, coupled with a large surface/volume ratio, means that they are not well adapted to survive adverse conditions, and, in particular, low relative humidities.
Control:
a) Hygiene/management
Because of the opportunities for re-infestation, booklice are difficult to control with insecticides. The most effective method of control is to ensure that premises are thoroughly aired and dry, thereby deterring the development of moulds and denying the insects their food source. Commodities should be stacked neatly above the
floor level using pallets, away from walls and should not touch the ceiling. A gap between stacks will allow for ventilation, regular inspection, cleaning and, if necessary, treatment with insecticides (see recommended products). Badly infested commodities should be destroyed. Infested pallets can be identified by ‘knocking
out’, i.e. dropping a pallet held end on about 75mm (3”) above a sheet of white paper.
b) Insecticidal control
Booklice are susceptible to a wide variety of insecticides (see recommended products). The problem lies in ensuring contact between the pests and the toxicant in order to bring infestations under control.
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Glossary of terms:
Tarsus (Tarsi): Apical section of leg (the foot).