Tom Lugzynski, age 12, of Missoula, Mont., for his question:

HOW DO FLEAS MULTIPLY?

Fleas are dangerous pests because they can transmit diseases to both men and animals. Fleas multiply through the laying of eggs. Eggs are deposited in the hair of animals or in cracks and corners where dirt can be found.

When the flea egg hatches, a little caterpillar like worm comes out and it spine itself into a cocoon. A flea finally crawls out of the cocoon.

There are hundreds of kinds of fleas. More than 50 species can be found in the United States and Canada alone. They annoy household pets, barnyard animals, tame and wild birds, squirrels, rats and nearly all other warm blooded animals.

Sometimes the eggs of cat and dog fleas drop off on a rug or upholstery in a house. When the fleas develop, they may then attack human beings. If pets are kept clean and dusted from time to time with flea powder, they will not bring fleas into the house.