Fleas and ticks are types of ectoparasites commonly found on the skin of companion animals. Despite their common names (eg, cat flea, dog flea, sheep tick), these parasites are not highly specific about which host animals they feed on.

Fleas are wingless insects that pass through a number of developmental stages: egg to larva, pupa, then adult. Adults are 1.5mm to 3mm and have long back legs which allow them to jump up to 30cm. Their adult mouth parts are adapted for piercing skin and sucking blood from warm-blooded host animals.

A couple of days after feeding on a host animal’s blood, female fleas will lay their eggs in batches of 20-50 a day.¹ The eggs are not attached to the host animal and can fall off and hatch elsewhere, typically three to five days after being laid.

Larvae are light sensitive, so tend to stay covered under bedding or carpets. To thrive, larvae need blood in their diet, which typically comes from adult flea faeces, as well as taking in nutrients from other dead insects, dust and detritus.¹

On pupating, adult fleas can emerge from the cocoon within a few days, or remain in suspended animation for a few months. Adults can live for 100-150 days if they are not removed from their blood food supply, so a flea’s whole lifespan could be 18 months. However, most adult fleas live only a couple of weeks, as grooming separates them from their host blood source.¹