There are plenty of reasons to dislike cockroaches. Their flattened bodies, leathery wings, skittering legs and long, waving antennae give some people the creeps. Because roaches eat garbage and waste, they can spread bacteria like Salmonella and Shigella from place to place. As they walk, they leave trails of fecal matter, which they use to find their way around. On top of being gross, these trails can cause stains and odors. The proteins in cockroach saliva and waste can also cause allergies and aggravate asthma.
People also hate roaches because they can be extremely difficult to get rid of. One reason is because of their natural behavior. They reproduce quickly and are hard to kill. Since they’re nocturnal, many people don’t notice their presence until there are so many that they’ve run out of places to hide. Roaches are particularly good at dodging and running from shoes, newspapers and other weapons, and several species have become resistant to insecticides.