Indian meal moths, also referred to as pantry moths, are a common pest of stored food products. The larvae of this insect feed on a variety of products including grains, nuts, cereals, dried fruit, bird seed, and even pet food. If an infestation occurs, it is usually recognized by seeing the small adult moths showing up all over the place. The moths can become a major nuisance and their larvae will quickly spoil any infested products. Indian meal moths can be a difficult pest to manage and often require time and persistence for successful elimination.
If you suspect an Indian meal moth infestation, it is important to first correctly identify the pest. The moths are a little over ¼ of an inch long with a wingspan of about ½ of an inch. They can be easily distinguished from other small moths based on their wing markings. Indian meal moths have a reddish-brown band on the outer half of their forewings, and a white or light gray band on the inner half (Figure 1). The two colors are separated by a dark band in the middle.
The larvae of Indian meal moths are typically yellowish-white with a brown head capsule (Figure 2). They vary in size depending on their growth stage, but are usually no longer than ½ of an inch. The larvae hang out in clusters and form webs as they grow. One of the key signs of an infestation is finding masses of silk webbing in stored grain or other products (Figure 3). There will also be visible feeding damage as well as frass (caterpillar droppings) left behind by the larvae.
Figure 2. Indian meal moth larva. Courtesy: Patrick Wagner
Figure 3. Indian meal moth larvae infesting a container of almonds. Courtesy: Patrick Wagner
Sanitation practices should be used initially to prevent an Indian meal moth infestation from occurring in the first place. Make sure stored food containers are closed and sealed properly. Throw out any old containers that do not have an air-tight seal. Open bags or boxes make it easy for Indian meal moths to get in and lay eggs. Sweep and vacuum up things like spilled grain or cereal and keep your food pantry clean and organized. Sometimes, Indian meal moths may even be brought in from the store if the storage warehouse that the items came from was dealing with an infestation. Be sure to check food containers for signs of Indian meal moth larvae (i.e., webbing) before purchasing or opening them at home.
Finding and eliminating the source of an Indian meal moth infestation is the best management strategy. If you find large numbers of adult moths in a garage, storage shed, or house (usually in the kitchen), there is likely an infested product nearby. Search containers of stored food along with pet food, bird seed, and even decorations made with natural materials like corn. Throw out infested products and be sure to take them outside to prevent possible re-infestation.
Until the source of an infestation is located, special traps can be used to reduce Indian meal moth populations. The traps are disposable sticky traps that emit the pheromones female Indian meal moths use to attract the male moths. The male moths will fly into the trap and get caught in the sticky substance surrounding the inside (Figure 4). This helps kill off many of the male moths to interrupt reproduction. Indian meal moth traps should be placed wherever the moths are most abundant. The traps are relatively inexpensive and can be purchased in most stores that sell over-the-counter insecticides.
Most Indian meal moth infestations can be resolved by finding and eliminating the source. However, severe or widespread infestations may require assistance from a professional pest control company.