Understanding the life cycle of the flea is necessary in order to control it. The flea has several stages to its life cycle. Adult fleas spend most of their time on the dog or cat - they must be dislodged to leave since they will not do so voluntarily. Despite this, when the flea population on the dog becomes excessive humans tend to be an acceptable alternative to the flea. The average life span of an adult flea is probably about 6 weeks - but fleas can live as long as a year under certain conditions. A female flea can lay 20 to 28 eggs a day. She may lay several hundred eggs over her life span. These eggs fall off the pet and develop where they land. They are small and can even develop in the cracks in wood floors or other small crevices. A larvae hatches from the flea egg. It takes as few as 9 days to as long as 200 days to go through its growth stages. At this time is forms a pupae and waits for the right time to hatch. Fleas prefer temperatures of 65 to 80 degrees and humidity of 75 to 85 per cent. This range determines the period of time that fleas are a problem in your particular area. For some areas of the country, this is all year. In others, the flea season is relatively short. It is estimated that for every adult flea found on the pet, there are about 10 developing fleas in the pet's environment.