What is a flea?
Fleas are wingless insects about 1.5 to 3.3 mm long, usually dark coloured that have mouth-parts adapted to feeding on the blood of their hosts. They have long legs and their hind pair legs are so well adapted for jumping that a flea can jump 18cm vertically and 33cm horizontally. This is their quickest mode of transport when not on your dog but they do not usually jump from one part of your dog to another. Fleas have laterally compressed bodies, making them thin to allow them easy movement through the hairs on a dog’s body. The flea has a hard and tough body that is covered with many backward facing hairs to assist in forward movement on the host and is able to withstand great pressure which makes it difficult to eliminate them by rubbing or scratching. Fleas can drown in water if submerged for long enough but usually they will move to the dog’s head when the dog is swimming.
Flea life cycle
Fleas go through the four life cycle stages of egg, larva, pupa, and adult. Adult fleas must first feed on blood before they can become capable of reproduction. They find a mate that is usually also on the same dog and then eggs are laid in batches of up to 20 on the dog itself, but eggs often roll onto the ground or dog’s bed and this becomes one of the main sources of eggs and developing fleas. The eggs take between two days to two weeks to hatch depending on the temperature and humidity so humid summer whether speeds up this process immensely.
Flea larvae emerge from the eggs to feed on any organic material they can such as dead insects, faeces, and plant material. They are blind but still avoid sunlight and hide in dark places like cracks, crevices, and bedding. Larvae will weave a silken cocoon and will morph or pupate into a pupa and the fully developed adult flea emerges from the cocoon. They remain in a resting state until they detect vibrations (including sound), heat, and carbon dioxide that let them know that a host is near. Fleas will overwinter in the larval or pupal stages for many months and then continue development when the weather warms up. Adult fleas only have about a week to find a host dog once they emerge from their cocoon, but after that they can stay alive for two years to three years between hosts. These characteristics of fleas allow them to remain with their hosts for generations and also allow fleas to live just about anywhere dogs can live. Female fleas can lay over 5000 eggs during their lifetime and this is one of the reasons why they can build up massive populations in short periods of time. Flea populations have a fairly even and stable distribution, with about 50% of the population being eggs, 35% larvae, 10% pupae, and 5% adults. This means that for every adult flea currently living on your dog or in their environment, there are another 20 fleas at different stages of their life cycle. Their complete life cycle can last only one year, but they can live and breed for several years in ideal conditions of 21°C to 30°C and 70% humidity.