Flea Life Cycle
The Flea Life Cycle Is A Strange One
The flea life cycle is a strange one indeed. Unlike the life cycles of many, and perhaps most other living creatures, the life span of a flea can vary from as few short weeks to several years, and each stage of its life cycle can also vary dramatically in time. One might wonder who would care anything about a flea's life cycle except perhaps a student who has been given the topic to do a term paper on.
People who should care would be homeowners and pet owners, especially if there is a flea problem. Pest exterminators usually are quite familiar with the flea life cycle as this knowledge is needed to effectively eliminate the pests. More about why this knowledge is important as we proceed.
The Flea Life Cycle Simplified - On the surface, the flea life cycle seems quite straightforward. Two fleas mate, and the female lays eggs. The eggs hatch and larvae emerge. The larvae, which look like tiny maggots survive on dried flea poop, molt 3 times, and then encapsulate themselves in cocoons. Inside the cocoons, the larvae go through a metamorphism, becoming creatures we would recognize as fleas. The newly formed fleas work their way out of their cocoons at which point they are full-fledged biting adults, and begin the search for their first blood meal. Once they find a host, they will live most of their adult life on that host.
So, how long does all of this take? This is where things start to get interesting. For some fleas, the entire process, from the time the egg is laid, until the flea dies, is around 3 weeks. At the other extreme, the life span from the time the egg is laid until the flea dies can be several years. Typically one or two years, but occasionally 4 or 5. It isn't that some fleas are healthier than others, or take better care of themselves, it’s a function of the environment they're in and circumstance.
The Egg - Let's start then with the flea egg. A female flea lays about 30 eggs a day, and perhaps an average of 600 in her brief adult life. An egg can take anywhere from just under 2 days to up to 2 weeks to hatch. This time span is largely influenced by temperature and humidity. The egg stage is the shortest of the life cycle stages for the flea.
The Larval Stage - The next life cycle stage is the larval stage. Over half of all living fleas at any one time are larvae. These are tiny legless creatures that look nothing like a mature flea. They feed off of dried flea excrement. Larvae do not bite or suck blood. From the time the larvae hatch until they spin themselves into cocoons, they will go through 3 molts, shedding their exterior shells for new ones. This period is when the fleas are most susceptible, having no real defenses, and depending upon dark and humid conditions in order to survive. This stage will last from 2 weeks to up to 6 months. It is not entirely clear why there is such a wide variation in the time period of this stage.
Cocoon And Metamorphosis- The larvae then build a cocoons where they will stay during the next stage, during which time they will make the transformation into adult fleas. The cocoon stage can last anywhere from 1 week to up to one year. This indicates that after a week or so in the cocoon, the larval transformation to an adult flea has been completed. The flea will not emerge from the cocoon however until something triggers the process. That something can be a vibration, the presence of carbon dioxide, or the presence of a host. Left in a more or less sterile environment, the flea may wait up to a year before emerging. This is the stage where the flea is safest, as the cocoon forms a protective shield against most chemicals and insecticides. When dusting for fleas, if they do not emerge from the cocoon when the insecticide is present and at full strength, they may be unaffected.
The Adult Fleas - Once emerging from the cocoon, the fleas are now biting adults and will go about seeking their first blood meal. One of the peculiarities of this stage is an adult flea can live up to a year, and perhaps 2 years, if it hasn't had its first blood meal. Once it has its first blood meal, it must eat again every 5 hours or so, or it will die. When an adult emerges from its cocoon, if it can't find food, it won't starve to death, and is less in danger of dying than it is once it finds food. On the average, a flea will have a life span of several weeks as an adult, and will usually stay on the same host during that time.
A Single Application Not Enough - Knowing all of this, one can understand why eliminating fleas can be such a problem at times. Depending upon the source you go to for your information, the number of adult biting fleas living at any one time represent somewhere between 1% and 5% of the total flea population. Most of the remaining fleas are still in the egg stage or in cocoons. When a flea insecticide is applied, the adults and the larvae may be killed off. The eggs and the pupae in the cocoons often survive, bringing along another crop of fleas later. That is why an exterminator may need two, and some times three applications of insecticide, to get the job completely done.