Sawtoothed Grain Beetle

(Oryzaephilus surinamensis)

Structure, Appearance and Characteristics Adults:

■    Small, active brown beetle about 2.5 – 3.5mm long.
■    Flattened body.
■    Well developed wings enable them to fly readily.
■    Edges of the thorax are saw-like and have 6 projections on each side.
■    Male is distinguished from the female by bearing a tooth on the femur of the hind leg.
■    Chewing mouthparts. Laveae (the young):
■    Yellowish white with a brown head.
■    Fully grown larvae are about 3-5mm in length.
■    It has 3 pairs of legs.
■    Chewing mouthparts. Life Cycle
■    Complete metamorphosis.
■    Female lays eggs singly or in small batches and deposited in the food supply and will lay from up to an average of 375 eggs.
■    Average incubation period of eggs is approx. 8 days.
■    Larvae moults 2 to 4 times.
■    Average larval period is approx. 37 days.
■    Average pupal period is approx. 6 days.
■    Development is more rapid at higher humidities.
■    Development cycle is approx. 3-4 weeks at optimum temperature 30 – 35 C.
■    Development cycle extends approx. 17 weeks at 20 C.
■    Development ceases below 17.5 C.
■    Adults can live up to three years.

Habitat
Commonly found in grain mills, stores and homes. Often found along with other insects which feed on larger grains. Does not breed readily in whole grain, but normally there is sufficient broken grains for infestation to occur. Food Cannot feed on whole kernels. Eats foods of vegetable origin such as cereals, dried fruits, breakfast foods, noodles, sugar, drugs, dried meats, tobacco. Pest Status Presence in products such as flour or cereals makes them unpalatable and unsaleable. Because of size, they easily enter packaged foods which can cause major infestation problems in grocery stores and other food processing plants. Both adults and larvae are considered pests since both live on the same food source.

Control
Strengths include a high reproductive rate, quick maturity to adult stage, high reproduction in the early stages of adulthood and easy dispersal and migration which means a new colony can start quickly with only a few individuals to begin. Weaknesses include the need for optimum temperature, moisture content and relative humidity before prolific breeding will occur.   Control measures include hygiene (incoming stock inspection, stock rotation, stock segregation, spillage control, warehouse design), aeration, drying, exclusion (screens etc.), chemical treatments (eg. surface sprays).  The objective of control measures is to STOP and infestation from occurring in the first instance. To remove a population from store products may require extreme measures such as fumigation or removal of the infected product from the premises followed by implementing adequate hygiene measures and chemical treatments to eliminate existing populations which may still exist in the storage area.  Being a secondary pest means direct treatment of the commodity may be much more difficult.