Frequently asked questions about insect pests in stored grain

1. How do I tell if I have grain that is infested with insect pests?

You can detect signs of an infestation by knowing about the life cycle of insect pests.

Read about eight common insect pests in stored grain and view photos of:

• The egg, larva, pupa and adult
• The insect feeding on grain

Using traps, probe sampling and sieves, and a Berlese funnel are three ways to sample grain and check for insects.

2. What products can I use once I discover that my grain is infested?

The Canadian Grain Commission recommends integrating control methods rather than only using chemicals to rid stored grain of insect pests. There are a variety of strategies for controlling infestations under different conditions and requirements:

• Physical control methods:
  • Grain vacuator
  • High temperature
  • Low temperature
  • Diatomaceous earth

• Chemical control methods:
  • Fumigating with phosphine or carbon dioxide
  • Applying malathion

3. How do I control insects when it is too cold to fumigate and not cold enough to use aeration to cause insect mortality?

There are several ways to control insects in this situation.

a) In the late fall, as the ambient air temperature drops:

• Use a pneumatic grain vacuator to move the grain and cause insect mortality. Pneumatic grain vacuators are shown to cause a high level of insect mortality.
• Ensure that the temperature of the grain is uniform and less than +15°C.
• Wait for the ambient air temperature to drop further and then aerate the grain to ensure insect mortality. (Using low temperature)

b) In the spring, as the ambient air temperature rises:

Use a grain vacuator in conjunction with fumigation to cause insect mortality. Before fumigating the grain, increase its temperature by either:

• Heating the grain with a dryer, (Using high temperature) or
• Aerating it with warm ambient air (How to use aeration systems)

4. What temperatures are necessary to cause mortality in stored product insect pests?

Low temperatures can be used to cause insect mortality over a period of time. The time period depends on the temperature of the grain. For example, if the temperature of grain is kept at -5°C for 12 weeks, stored insect pests will be controlled at all life stages. Read time periods for disinfesting grain at low temperatures.

Grain temperatures above +40°C will kill insects at all life stages. Read how to use a grain dryer to cause insect mortality.