ANTS, unlike roaches, usually do not directly infest a building. They live in nests below ground, but can, if given the right conditions, create a secondary nest in the floors or walls of a building. The reason the ants enter the house is to find food and water. Again like roaches the main concern is the unsanitary conditions they can spread. Fleas are known to be profound jumpers and can leap more than a foot from the ground.
Fleas are most common during the warmer months of the year.