Bug bombs or foggers are convenient and easy to use. However, they are not effective against most household insect pests and might cause problems, especially when people don't follow label directions for proper application.

"Homeowners have many tools available to wage war against insect pests at home. But bombs or foggers aren't our recommended way to combat bugs," said Mike Potter, Extension entomologist with the University of Kentucky College of Agriculture.

"Foggers are not effective against indoor pest problems because the aerosol insecticide droplets do not effectively penetrate cracks, wall voids and other hidden locations where most household pests congregate. Instead, the droplets land primarily on floors, counter tops and other exposed surfaces," Potter said.

Pyrethrum is the primary active ingredient in many insect foggers. Although fairly effective against flying insects such as mosquitoes and houseflies, pyrethrum is seldom lethal to cockroaches, ants, spiders, beetles and other crawling pests. Furthermore, bug bomb ingredients tend to be repellent, causing pests to scatter and move further into wall voids and other hard-to-reach areas.

The bombs also have the potential to cause difficulties above and beyond the existing bug problems, according to Potter.

"The ingredients in aerosol insecticide products may be flammable when used or stored near an open flame such as a pilot light, cigarette or the like. A house fire can result when homeowners neglect to extinguish these open flames before using the fogger," he said.

"Other problems can emerge if people don't read and follow instructions on using bug bombs," Potter added. "For instance, instructions state that exposed food, utensils, food preparation equipment and working surfaces should be covered before a bomb is used. They also should be cleaned afterwards. Yet many people fail to read and follow these directions.

"Another potential problem is that pyrethrum is considered a 'natural' and 'safe' ingredient because it comes from chrysanthemum flowers. However, people with asthma and other respiratory ailments can have a serious reaction when pyrethrum or other irritating and volatile compounds are used indoors. Label instructions state that people and pets should not remain in the treated area, but they aren't necessarily required to leave the home. In an extreme situation, people or pets remaining in the home could have a serious reaction."

Potter said bug bombs might be useful when cluster flies or paper wasps infest attics, outbuildings or other cluttered, hard-to-reach areas.

When an insecticide is needed to eliminate a pest problem, a spray, bait or dust is more effective against all varieties of household pests, including fleas, when it is put directly into areas where pests are hiding, according to Potter. Flea control products that can be dispensed by hand can be targeted to locations that are less accessible to foggers.

"County Extension offices have many publications to help you identify and deal with specific household pests. Depending upon the insect pest you're trying to control, a broom or vacuum cleaner might be just as effective as an insecticide," he said.