How Large Do Fleas Grow?

Fleas grow to about one-eighth inch long in their adult stage. These creatures start their life cycle as a small, semitransparent egg. These eggs develop over about four to eight days and will hatch once the environmental conditions are right. After hatching, they will develop into a pupa that is about an eighth inch long and reddish brown to black in color. They are flat and do not have wings, but they do have long back legs to jump from one host to another.

Fleas have three pairs of legs, with the middle pair large and adapted for jumping. Their thorax consists of three segments that overlap one another to make it easier to squeeze. The front of their body is flat, and their legs are made of hard, shiny substance that helps them move through the fur.

Adult female fleas lay up to fifty eggs per day. The eggs are very difficult to see with the naked eye, but when they are mature, they take on a darker color and are more visible. Once they hatch, they stay in their host for a week or more, during which time they will begin to feed off the host’s skin cells and other debris.

As an adult flea, fleas are different in size, and they are dependent on the nutrients they receive and their genetic make-up. Their chitin exoskeleton is what stops them from growing larger than they are.