Merchant Grain Beetle

Scientific Name:Oryzaephilus mercator (Fauvel)
CLASS/ORDER/FAMILY: Insecta/Coleoptera/Cucujidae
METAMORPHOSIS: Complete

Introduction:

The merchant grain beetle is very similar to the sawtoothed grain beetle in appearance, life cycle, and habits. For years they were considered 1 species until breeding experiments showed they were 2 different species. This pest is worldwide in distribution and can tolerate the cooler climates.

Recognition

Adults about 1/8" (3 mm) long, with flattened body. Color dark brown. With 6 sawlike teeth on each side of prothorax. Length of temple (region directly behind eyes) less than half the vertical diameter of eye. With well-developed wings, and known to fly.

Mature larva yellowish white. Less than 1/8" (3 mm) long. Elongate, without urogornphi (paired processes projecting from last abdominal segment), relatively smooth. Antennae 3-segmented with 2nd segment longest and 3rd very small. The sawtoothed, foreign, and squarenecked grain beetles share this same description.

Similar Groups

(1) Sawtoothed grain beetle (Oryzaephilus surinamensis) with length of temple (region directly behind eye) greater than half the vertical diameter of eye.

(2) Other small dark flat beetles lack 6 sawlike teeth on each side of thorax.

Biology

Tiny sawtoothed grain beetles and the closely related merchant grain beetles are found throughout the world. These beetles attack such foods as cereals, breakfast foods, biscuit mixes, sugar, macaroni, flour, rice, dried meats, and dried fruits. They are primarily found where these dry foodstuffs are stored. Their presence in food makes it undesirable for human consumption. No diseases are associated with the insects. The beetles are unable to break or eat through hard shelled seeds such as corn, but they may be found in grain containing broken kernels or in processed cereal products.

Grain beetles are most likely to be found in foods that are stored for long periods. Food containers that are replenished without first emptying and cleaning the containers are susceptible to infestation. Cereals and flours are most likely to be infested.

The adult beetles are brown and about an 1/8″ (2.5mm) long. Their flat, narrow bodies make it easy for them to enter cracks in storage areas or packaged materials. The thorax, the middle section of the beetle’s body, has saw-like projections on each side. Although they have fully developed wings, the beetles rarely fly. The worm-like larva is yellowish white, with a black head and three pairs of legs. A mature larva is about 1/8″.

Habits

The merchant grain beetle cannot attack sound kernels. Its flat body form permits access through very small cracks and into imperfectly sealed packages. The merchant grain beetle flies; while the Saw-Tooth does not fly. These grain beetles can fly to new food sources, instead of just normal transport. Both of these grain beetles are found in kitchens, food processing areas or warehouses.As the Saw-tooth Beetle, Merchant Grain Beetles don't eat whole grains. They prefer the smaller broken particles and are attracted to higher fat products.They can infest and contaminate breakfast foods, cereals, macaroni, candy, chocolate, sugar, cake mixes, brownie mixes, ntus, dried pet food, bread, rolled oats, biscuits, cornmeal, etc.

Adults can fly and they are attracted to light.
It is not commonly found in grains, but appears to prefer oilseed products, including nuts and cereal products. It most commonly attacks cereals including rolled oats, rice flour, cake mixes, macaroni, and cookies. It has also been found infesting nuts, coconut, and candy bars made with peanuts and puffed rice.

Control

There are a huge variety of stored product pests known as pantry beetles or pantry weevils. We go into some detail on some of the most common, The Confused Flour Beetle, Red Flour Beetle, Cigarette Beetle, Drugstore Beetle, Sawtooth Beetle, and Merchant Grain Beetle. These beetles feed on a wide range of food products, including pet foods, cereals, cookies, candy, nuts, dried legumes, pastas, spices, potato chips, crakers, dead insects and even dead animals. The lesser grain borere, the bean weevil , the granary weevil and the rice weevils feed mostly on whole grains and seeds. The weevils are less likely to feed on cereals and grains, unless it has become caked and hardened.The control and management would be similar for both pantry beetles or the pantry weevils.

Inspect and Discard: Look for signs of their infestations. Look in particular the higher fat items in the pantry like cake mixes, chocolate, bran, brown rice, rolled oats and items that have been in storage for a long time. The Merchant Grain Beetle, like the Saw-Tooth Beetle, are not able to feed off hard shelled pantry items like whole grains, or hard shelled seeds such as corn. They can be found in these items if the grain has been broken. Clean and Vacuum: After inspection and dicarding infested items, clean and vacuum cracks and crevices and shelves. Don't forget to clean and vacuum under the shelves and any wire shelving.

Clean and Vacuum: After inspection and dicarding infested items, clean and vacuum cracks and crevices and shelves. Don't forget to clean and vacuum under the shelves and any wire shelving.

Use Pheromone Traps: These traps have a sex pheromone in order to catch and trap male cigarette beetles. They will also attract male moths. Place only a couple of traps in the kitchen or pantry

Use Insecticide Aerosols: This is to be done after cleaning and before placing the foodstuffs back on the shelves. They will help prevent furture infestations in the cracks and crevices. For larger areas, use insecticide concentrations