Know the Enemy: Stored Grain Insect Identification

Before you start a plan of attack to get rid of unwanted bugs in grain, you need to know just who you’re fighting against. Knowing how to properly identify stored grain insects ensures you’re using the right products, in the right spots, at the right time— boosting your control power. Pay attention to the insects you come across around your operation. There are seven common stored grain pests and Central Life Sciences would like to help you identify them, leading to increased grain protection which equates to increased profit protection. Check out profiles on those seven bugs below and get started identifying your pest. Don’t see your invader? Send a picture to our team and we’ll identify, as well as offer a product plan that’s right for you.

Weevils are one of the hardest stored product pests to control and one of the easiest to identify due to their distinct snout, as well as the iconic damage they cause to grain. Creating a “shot hole” appearance, the adult weevil bores a small hole on the surface of the grain kernel, lays an egg, then covers the egg with a gelatinous fluid. This process makes control of immature weevils very difficult. The immature weevils consume the kernel interior and within approximately 4 weeks, the immature changes into an adult weevil in the kernel interior. When the adult weevil emerges from the kernel interior, a hollow kernel remains. An adult weevil’s lifespan ranges from 7-8 months and females can lay between 50 to 250 eggs.

Rice Weevils
Strong fliers and internal feeders, rice weevils possess four light-red-to-yellow markings on their forewings and have a densely-pitted thorax. Infesting stored grains as primary feeders, rice weevil infestations typically start in the field. In storage, the weevil can easily move throughout the storage facility destroying whole grain.

Granary Weevils
Typically, smaller than the rice weevil, the adult granary weevils do not have wings or markings on forewings. Since these weevils do not fly, infestations are linked to localized infestations at the storage site and infested grain transportation systems, underscoring the need to treat trucks and equipment for insects.

Lesser Grain Borer
With its head tucked underneath its thorax, the lesser grain borer has strong flying capabilities and like weevils, creates “shot holes” in the internal kernel of grain. Lesser grain borers are known for how destructive they can be, leaving piles of grain dust behind them as well as a sweet musty odor in grain. These prolific breeders are able to lay up to 500 eggs during their life cycle of about 2 months.

Saw-Toothed Grain Beetle
This pest gets its name from the distinct saw-toothed projections on the sides of its thorax. Flightless with running legs similar to a cockroach, saw-toothed grain beetles are secondary pests and can be found infesting oats, wheat, barley and animal feeds. The adult lifespan ranges from 6-10 months, and populations can build up quickly with these primary feeders. Saw-toothed grain beetles congregate in areas together, and these congregations creates hot spots in grain.

Confused Flour Beetle
This reddish brown, flattened beetle is nearly identical to the red flour beetle. Under magnification the antennae gradually increase in size from the base to the tip. Confused flour beetles are flightless insects and typically live longer than 18 months. During feeding, confused flour beetles contaminate commodities with shed skins, and fecal matter, which creates a foul odor and taste in commodities. As a general feeder, confused flour beetles feed on grain dust, broken kernels and milled grains in flour and cereal mills. These flightless pests are often found on the floor and crawling on equipment.

Red Flour Beetle
Unlike the confused flour beetle, red flour beetles are able to fly and have three distinct clubs at the end of their antennae. A scavenger and secondary feeder, these insects feed on broken or damaged grains, rather than attacking the kernel of the grain. Because of their feeding habits, red flour beetles are usually found in mills and warehouses that store grain products. These invaders can live up to 18 months and cause commodities to have a pungent odor, foul taste and even a pink coloration, destroying profits.

Indian Meal Moth
The Indian meal moth is a small brownish moth featuring a distinct reddish-brown with copper luster on the outer portion of the forewing. The Indian meal moth can be spotted flying near the grain bin, by their larvae climbing up walls inside bins or by the dense webbing left on food fragments by larvae. Larvae are typically top feeders, and will be found between four and six inches of the surface. The immature stages typically last between 6-8 weeks, and the adults typically die within a week of laying eggs. Want to learn more? Check out our complete insect-id


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