SCHAUMBURG, ILL.  — While the kinds of pests that attack stored foods have not differed over the years, some are becoming more prevalent.

“These pests have been around a long time and haven’t changed much,” said Mel Whitson, regional manager and degreed entomologist, Central Life Sciences, Schaumburg, Ill. However, some invasive ant species are now showing up in California and Florida.

“While these are aggressive species, they are usually considered secondary pests,” he said.

Far more destructive are the insects that break through the tough hulls of cereal grains and expose the interior to moisture, mold and fungus. In some parts of the world, grain and rice weevils damage up to 40% of the crop.

The insects found in bakeries are usually beetles — the red and confused flour beetles — and the Indianmeal moth, which is very common in grain stores and retail environments, noted Raj Hulasare, Ph.D., PEng (Canada), senior scientist and product manager, Temp Air, Inc., Burnsville, Minn.

“In snack food facilities, the species varies according to the type of food stored and processed, with flour, cigarette and warehouse beetles the most common,” Mr. Hulsare said.

Stored-product pests are not like rodents and flies because they are not heavily affected by the weather, said Zia Siddiqi, Ph.D., director of quality systems, Orkin, a subsidiary of Rollins, Inc., Atlanta.

“Stored-product pests also don’t usually pressure facilities from the outside,” he said. “Instead, they often hitch a ride into a facility on shipments from suppliers.”