Do Grain Beetles Fly? Uncovering the Truth About These Pests

Grain beetles are common pests in stored grains and can pose a significant problem for agriculture. There are a few different species of grain beetles, including sawtoothed grain beetles and merchant grain beetles, which have slightly different life cycles and behaviors. Knowing whether these beetles can fly is important for understanding their potential to spread and infest grain storage facilities.

The foreign grain beetle is a small reddish-brown insect, often mistaken for fruit flies or gnats due to their strong flying ability. On the other hand, sawtoothed and merchant grain beetles, despite having wings, are not known for their flying prowess.

Do Grain Beetles Fly

Sawtoothed Grain Beetle vs Merchant Grain Beetle

Grain beetles are common pests found in stored products, specifically infesting broken grain and processed grain products. Among the grain beetles, there are two primary species: the sawtoothed grain beetle and the merchant grain beetle.

Sawtoothed Grain Beetle

• Scientific name: Oryzaephilus surinamensis
• Appearance: Saw-like projections on the pronotum
• Flight: Does not fly
• Attraction to light: Not attracted to light

The sawtoothed grain beetle is not capable of flight, and they are not attracted to light. These beetles are named after the saw-like projections found on their pronotum.

Merchant Grain Beetle

• Scientific name: Oryzaephilus mercator
• Appearance: Similar to sawtoothed grain beetle, without saw-like projections
• Flight: Capable of flight
• Attraction to light: Attracted to light

On the other hand, the merchant grain beetle is indeed capable of flight, and they prefer light. These beetles are closely related to the sawtoothed grain beetle but lack the characteristic saw-like projections.

Comparison Table

In summary, sawtoothed grain beetles do not fly and are not attracted to light, while merchant grain beetles can fly and are attracted to light.

Grain Beetle Identification

Physical Characteristics

Grain beetles are small with a flattened body shape, typically measuring between 1/10 and 1/8 inch in length. They are brown or reddish-brown in color. Their flat bodies make it easy for them to crawl into tiny crevices. Some grain beetles have distinct features, such as saw-like projections or peg-like structures behind their head. To identify grain beetles, entomologists often use a magnifying glass to examine these features more closely.

Common Types of Grain Beetles

There are two common types of grain beetles that are often encountered in households: sawtoothed grain beetles (Oryzaephilus surinamensis) and merchant grain beetles (Oryzaephilus mercator).

• Sawtoothed grain beetles have six saw-like teeth on the first segment behind the head.
• Merchant grain beetles have two peg-like projections behind their head.

These two grain beetles have similar sizes, colors, and body shapes, which can make it challenging to distinguish them without using a magnifying glass to examine the mentioned unique features. Below is a comparison table illustrating key differences:

(*) Some sources mention that sawtoothed grain beetles do not fly, while others mention that merchant grain beetle can fly. However, this information may vary between sources and individual specimens.

When dealing with a grain beetle infestation, it is essential to correctly identify the beetle type to decide on the most effective control method. In case of doubt, consult an entomologist or pest control professional for assistance.

Life Cycle and Habits

From Egg to Adult

Grain beetles go through a complete metamorphosis during their life cycle, which includes egg, larvae, pupa, and adult stages.

• First form: egg
• Second form: larvae
• Third form: pupa
• Fourth form: adult

The length of the life cycle can vary among different species of grain beetles. Some may take 2-5 years to complete their life cycle, while others may have several generations within a year¹. In general, a beetle stays in the egg stage for about 7-10 days before they hatch into larvae².

Larvae stage is where grain beetles undergo rapid growth. Like mealworms, the larvae of some species are used as a food source for animals³.

Next comes the pupa stage, during which beetles transform into their adult form. The duration of pupal stage varies depending on the species and environmental factors.

Once they reach the adult stage, grain beetles are capable of flying⁴. They are attracted to grains and other stored food products, making them a nuisance in households and commercial premises.

Table 1: Comparison of Grain Beetle life stages

Causes of Infestation

Pantry Pests

Grain beetles are a common type of pantry pest that can infest a variety of stored food products. They are attracted to cereals, nuts, pasta, dried fruits, chocolate, bread, and sugar. These pests can infest food containers that are replenished without being emptied and cleaned first.

Two types of grain beetles include:

• Foreign grain beetles: Small, flattened, reddish-brown insects, about 1/12 inch long. They can be identified by two peg-like projections behind their heads ¹.
• Sawtoothed and merchant grain beetles:

Damage and Harmful Effects

Impact on Grains

Grain beetles are a significant problem for stored grain products. These insects have hard shells and can fly, making them difficult to handle and control ¹. Some examples of products they infest include:

• Grains
• Flour
• Pet food
• Drugs
• Tobacco

Grain beetles can cause significant damage to these products by:

• Contaminating them with their excrement
• Feeding on and reducing the weight of the grains
• Introducing mold and fungi

Stored Products

When grain beetles infest stored products, they can result in economic losses for businesses and households. They are known to cause the following issues:

• Reduction in quality of stored products
• Shortened shelf life due to contamination
• Increased costs for pest control and product replacement

Comparison Table:

By better understanding the damage and harmful effects of grain beetles, individuals and businesses can take appropriate measures to manage and prevent infestations.

Prevention and Control

Sanitation and Food Storage

• Make sure to inspect your pantry regularly for any signs of grain beetles.
• Clean your shelves and pantry regularly to prevent grain beetles from hiding and breeding.
• Store food items in tightly sealed plastic containers to avoid infestations.
• Dispose of infested food items immediately.

An example of proper food storage methods:

Pest Management Practices

• Keep an eye out for grain beetles in small cracks and crevices around your home.
• Use a vacuum to clean up any beetles you find while cleaning or inspecting your home.
• Consult professional exterminators if the infestation gets out of hand.

As humans, we play a big role in pest prevention and management. Proper sanitation practices, food storage methods, and professional pest management assistance are crucial for keeping grain beetles under control. It’s essential to take these steps to maintain a clean and beetle-free environment.

Treatments and Solutions

Insecticides

Insecticides are an effective way to control grain beetle infestations. Two common insecticides used for this purpose include:

• Pyrethrin: A natural insecticide derived from chrysanthemum flowers. It is effective against many stored product pests like grain beetles and weevils.
• Malathion: A synthetic insecticide used to control various insects, including saw-toothed grain beetles and weevils.

Pros:

• Effective in controlling infestations.
• Wide range of products available for different pests.

Cons:

• May require multiple applications.
• Some insects may develop resistance over time.

Aerosols

Aerosols, such as Novacide, can also help address grain beetle infestations. They are typically applied in areas where the beetles are active, such as stored grain or product storage spaces.

Pros:

• Easy to apply.
• Can quickly kill exposed beetles.

Cons:

• Less effective for deep infestations.
• May require reapplication over time.

When dealing with grain beetle infestations, it’s also essential to:

• Practice good sanitation by vacuuming and cleaning areas where grain is stored.
• Monitor for pests regularly.
• Ensure proper storage and handling of grains to reduce the risk of reinfestation.

Further Resources and Assistance

If you’re looking for resources on grain beetles, UMN Extension offers information on identifying and managing foreign grain beetles. These beetles are small, flattened, reddish-brown insects with peg-like projections behind their heads. They can be mistaken for fruit flies or gnats.

To differentiate between grain beetles and other insects, note that beetles have a hard shell, unlike flies. Additionally, [UMaine Cooperative Extension](https://extension.umaine.edu/ipm/ipddl/publications/5034