The species most encountered by pest management professionals is the cat flea, and the majority of the information listed here will pertain to the cat flea.  Do not let the name of the pest mislead you.  Cat fleas prefer the temperature of a cat’s blood but will feed on the blood host of most warm blooded nesting animals found in and around homes in the United States. 

Fleas develop through a life cycle known as a complete metamorphosis, beginning with the flea egg.  This smallest stage of the flea’s life cycle is seldom seen, due to its small size.  These tiny eggs are well distributed by the host of the flea (dogs, cats, nesting animals) and should be considered in any flea control program.  Knowing flea egg development will give you a better understanding of the pest and aid in flea control and flea prevention.

Flea eggs are small, only about 1/50 inch long.  They are smooth and translucent.  When found in high numbers along with flea fecal matter, the eggs are “salt” in the “salt and pepper” look of these tiny particles.  People often report seeing particles (sometimes called “flea dirt”) that slightly resemble salt and pepper in pet bedding or in locations frequented by their pets.  Many people confuse the two, believing the small, dark objects to be flea eggs. 

As will be discussed in adult flea information, the female adult flea consumes far more blood from her host than her body needs.  The excess she excretes in tiny droplets that quickly harden.  These hardened, dried drops of blood serve as food for immature, flea larvae.  When larvae hatch from flea eggs, they will need a food source.  This is why flea eggs and adult flea droppings are often found in close proximity.  As animals scratch, shake or jump off of furniture these fecal droppings and flea eggs fall off of the host.

Whereas some parasites of warm blooded animals have a method of adhering their eggs to the hair of their host, flea eggs lack any sort of sticky substance which would allow this.  The eggs fall off of their host as the host moves, scratches itself, grooms itself and with other types of motion.  House pets that jump up on and down from furniture in our homes help distribute the eggs as the pets move around in their favorite areas of the home.  The eggs are tiny enough to roll off of their host and fall into seams, between cushions of furniture and other areas where normal vacuuming does not always reach.  This is important to remember when controlling fleas or preventing flea infestations in your home.

Most development of immature fleas (in their various stages) is directly related to temperature, relative humidity, carbon dioxide, movement and vibrations.  Flea eggs are no exception to the rule.  As the temperature and humidity of its surrounding environment are lowered, so too are the number of relative number of flea eggs that will survive and hatch.  With temperatures dipping below 50 degrees Fahrenheit, the percentage of fleas hatching also falls.  The eggs can rarely survive in freezing temperatures.

Flea eggs can hatch as quickly as 2 days and as late as 2 weeks when humidity is over 70% and temperatures are between 80 degrees and 90 degrees.  When the eggs hatch, the larval stage of the flea emerges.  Eggs that are exposed to an environment that is kept at a constant 50 degrees or less will usually die in less than 2 weeks.  Flea pupae have a far better capability of surviving in bitter conditions.

A tremendous number of flea eggs are laid in an infested home or lawn, as will be discussed in the section “adult fleas.”  Many people worry about the exact “cycle” of fleas when trying to exterminate fleas in their home.  Locations of immature insects and their capabilities are more important information than the life cycle of one single pest!

As your pet runs, jumps, eats, sleeps in your home it is helping to distribute flea eggs about the house.  A thorough cleaning and vacuuming will help pick up many of the eggs, making sanitation job number one in flea prevention and flea control.  If there is a favorite bed, couch or chair that a dog or cat prefers to jump on, there will be a more intense population of flea eggs under and around that piece of furniture!  Flea eggs, flea larvae and flea pupae can be found in large numbers at these locations.  It is rarely a good idea to treat only isolated rooms of a flea infested home.  Clean and treat the entire house while paying close attention to these flea hot spots.  Vacuuming not only picks up flea eggs but also removes a great deal of the dried blood needed as a food source for the next stage of the flea’s development: flea larvae.

It is important to use a flea insect growth regulator (IGR) inside the home.  Insect growth regulators do not directly kill adult insects and do not kill adult fleas. An IGR overloads flea eggs and flea larvae with a juvenile hormone mimic – in other words, immature fleas exposed to an IGR will not grow up or develop into fully developed adult fleas.  Insect growth regulators can be used alone (for flea prevention) or combined with an insecticide that is approved for indoor flea control. 

We can kill adult fleas with pesticides and we can prevent flea eggs and flea larvae from becoming biting pests but there are no chemicals available that can effectively penetrate the cocoon or pupal stage of the flea.  Patience, thorough sanitation, prevention and use of approved products are all needed to rid your home of fleas.  Understanding the capabilities of each stage of the flea gives you the knowledge to safely get the job done.  Patience and understanding will help you get through the aggravation of the flea pupae stage.  Prevent fleas from becoming pests by targeting the egg and larval stages.