Interior plastic liners like those used in breakfast cereal boxes can be effective, blocking air from carrying aromas outside to hungry insects. In 1991, Mullen helped to develop an odor neutralizer that can be incorporated into packaging materials. He devised a laboratory choice test allowing insects to choose between a food protected by the odor neutralizer or by only untreated packaging. They chose the food in untreated paper. Each additional improvement added to the package design helps keep insects out.
All packages provide some protection against invasion.
Mullen has developed scientifically proven methods to evaluate packaging materials against insects in the laboratory. He places 32 to 40 of each package type in an environmentally controlled room for about 3 months. These packages are exposed to five species of insects. Each month, the researchers examine packages for holes and flaws in seams and closures. Finally, they open the packages and examine the contents for insect infestations.