Life Cycles of Different Pantry Pests

Pantry pests are usually brought into your home through infested food packages. You may not notice an infestation easily because the pests are quite small, particularly in their larval and egg forms. A common indication of a pest infestation is often the presence of small moths flying around or beetles near or in food packages.

Life Cycles and How to Identify Pantry Pests

Adult beetles and moths are easy to differentiate. However, the larvae of these pests are a bit harder to identify.  You can use a hand lens to inspect the larvae’s legs. Moth larvae have three pairs of true legs and extra leg-like structures.

Beetle larvae are legless and grub-like or may have only three pairs of legs located close to their head. Only the moth larvae feed on stored products, while both adult and larval stages of beetles feed on food items.

1.      Pantry Beetles

The larvae of pantry beetles are about 1/4" long when fully mature and have plenty of hairs or stiff setae on the last fragments of their abdomen. The tip of their abdomen is also covered with long thin hairs.

Adult beetles are about 1/8" long and have oval bodies. Their wind covers have a yellowish and brown pattern. Female beetles can lay up to ninety eggs in the infested food items.

They are extremely active and always look for a new food source to infest. The entire life cycle of pantry beetles can be completed within forty-five days in warm temperatures.

They shed their hairs within the infested food items. The hairs can be irritating to the digestive tract, mouth and esophagus if ingested. Infested food should be thrown away.

2.      Meal Moths

Indianmeal moths have reddish brown forewings. The outer two-thirds of their forewings have a coppery sheen. Their body or the inner portion of their forewings are whitish gray.

Only the larvae cause damage by feeding on various food products such as dried fruits, candies, pet food, dehydrated vegetables, cornmeal, cereal, rice, nuts and chocolate. Adult moths don’t feed.

If you have a heavy moth infestation, you will notice mature larvae in parts of your home far from the original source of food as they move some distance to pupate.

The female moth lays eggs in groups or alone on food items. Moth egg hatches within a few days into a small caterpillar that is whitish in colour. The larvae of Indian meal moths leave silken threads behind when they move out.

The larvae spin a silken cocoon and transform into a pupa that is light brown in colour. The moth emerges from the pupa. Indian meal moths take about six to eight weeks to complete its life cycle during warm weather.

3.      Flour Beetles

Flour beetles include the Tribolium confusum or the confused flour beetle and the Tribolium castaneum or the red flour beetle. Within a year, about five generations of these pests are produced. Females deposit the eggs into the grain products.

These eggs are difficult to see by using the naked eye. It takes about six to a maximum of eight weeks for eggs to transform into adults. Once they reach their adult stage, they can live for up to one year.

4.      Saw Toothed Grain Beetles

Females lay their eggs in small batches or individually within or around the area where the food supply is. An adult female can lay around 45 to about 285 eggs every year.

After 3 to 10 days, larvae will start emerging from the eggs. These will mature within a period of 50 days.

Adult females are able to live for about 10 months but can reach a year under ideal living conditions. Since their cycle only requires a short time for adults to develop, several generations are produced annually.

5.      Cigarette & Drugstore Beetles

Females usually lay about 100 eggs within a span of 6 to 20 days. They lay their eggs in the depressions, crevices, or folds of their food. The time for development depends mostly on the environmental conditions as well as the food source.

Commonly, the development will take about 50 days to more than 100 days. The optimal conditions for their development are temperatures ranging from 20°C to 30°C and 70 to 80% RH. Development may slow down when the temperature is below 15°C or more than 34°C.

They usually go through four to six larval instars. Larvae that newly emerge are the ones very active and able to enter food packaging even in the smallest holes. They construct pupal cells within their food sources and enter pupation until they emerge as adults.

6.      Bean Weevils

Since these pests feed on bean pods, females usually deposit eggs on these pods found in the field or those stored whole beans. Every adult female can lay about 60 eggs throughout their lifetime.

Because of their small size, larvae can go through every bean and eat a portion of the bean. The larvae are the one making a lot of damage in beans. Adults are not the ones eating the beans.

Once they reach maturity, the larvae will enter pupal stages near the bean’s surface. As they leave the beam, the larvae will leave a lot of holes. One complete life cycle can take about 21 days and last for 80 days.

7.      Spider Beetles

Larvae and adult spider beetles are all scavengers. They lay their eggs inside rodent droppings, bird seeds, hair, wool, feathers, and dried meats and fruits.

Once the larvae emerge, they keep on feeding and growing. When feeding, the larvae will spin a silken web and spin cocoons. They use this when transforming into adults.

As soon as they reach the adult phase, they come out of the cocoons and search for a mate. The length of time for development always depends on the source of food and the temperature in the environment.

How to Detect Pantry Pests

If you see beetles or small moths flying or crawling around the kitchen, you should find the source of the infestation and get rid of it immediately. Control may be easier if you find the source before the infestation spreads to other food packages.

The source is usually a package damaged at the store. It may also be an opened food package that’s forgotten or little used. You should seal up the package and throw it away immediately.

Damage Caused by Pantry Pests

Pantry pests contaminate food with their body as well as by-products. Some beetle larvae secrete substances that give foods an unpleasant taste or odor. The larvae of Indian meal moths produce webbing and frass or excrement. Warehouse beetles shed hairs that can irritate the throat, stomach, and mouth of those who consume infested products.

How to Manage Pantry Pests

Eliminating pantry pests takes continuous effort, especially if the infestation has been happening for a while. You have to be tenacious as well.

Some pests can live for weeks without consuming anything, so the possibility of an infestation exists until the pests are killed or die off. You should follow the guidelines for cleaning up and removing an infestation.

Keep vulnerable food items in the freezer or airtight containers for several months after getting rid of the infested products. Keep food items in the freezer to prevent an infestation. Examples of food items that are not often used are spices, pancakes, grains, and flour.