An aerosol is a spray of very fine particles, designed to stay suspended in the air for some time. By staying suspended, the fine particles have the maximum opportunity to touch an insect. Larger particles would fall to the ground faster and be far less effective. Aerosols are particularly effective in confined spaces, the trade-off being that such small dosages and the minute particles have very little residual effect. Aerosols control a variety of household insects such as flies, moths, mosquitos and fleas, but can only kill the insect they touch. They are relatively ineffective against larvae and eggs, bedbugs and carpet beetles.