PPC Environmental Limited

Belfast | N'Ards

Spider Beetles

Spider beetle larvae will infest all manner of dry animal and vegetable matter including grain, spices, fish meal, dog biscuits, dried fruit and a wide variety of miscellaneous debris. They will scavenge among the debris of neglected stores, and have even been reported infesting insecticidal derris powder. The larvae bore holes in which to pupate, and in so doing may damage packaging or the commodities themselves. They also contaminate commodities with droppings and silk webbing.

Adult beetles, too, will damage packaging including bags and sacks. Gregarious and nocturnal, they spend the day in cracks and crevices amongst packaging and the fabric of the store. Consequently they can thrive in old buildings where they find many harbourages.



Assessment of infestations A variety of trapping techniques are available for measuring stored product beetle infestations. These include pit fall traps, bait bags, insect probe traps and adhesive traps. Whatever system is employed adequate records must be kept.


(A) Hygiene / Management

Stores should be soundly constructed to ensure maintenance of correct storage conditions and allow for easy cleaning. They should be insulated, well ventilated and damp-proof. Cracks and crevices, which may provide harbourages for the beetles, should be kept to a minimum.

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.

Appropriate stock rotation is important and if possible there should be a one-way passage of commodities through the premises. The careful choice of packaging can help to deter insect attack. Generally, thick, tough materials with a smooth, shiny finish are preferred. Packs should be strong and well sealed.

It is important to ensure that there are no food residues (stored commodities or secondary sources, e.g. birds’ nests) in which beetles can breed and develop to infest new materials. All infested commodities should be destroyed or fumigated. Stores should be kept scrupulously clean and farm stores should be thoroughly cleaned before harvest.

All grain taken into store should be dried to a suitable moisture content (MC) and temperature eg. <15%MC AND <15°C and maintained in that condition.


(B) Insecticidal Control

Insecticides can be applied to the fabric of stores concentrating on potential insect harbourages. Alternatively it may be appropriate to employ grain protectants.