Ticks are solely blood-sucking parasites that feed exclusively on blood of vertebrates. They belong to the Class Arachnida (same class as spiders, scorpions and mites), Order Acarina (mites and ticks). Their body is a single structure, with no apparent divisions.

The tick development cycle consists of egg, larva (three pairs of legs), nymph (four pairs of legs) and adult. They generally mate on the host animal, but the female oviposits on the ground, even though due to her habit of crawling upward, she may also lay in cracks and walls.

The adult female feeds only once and can lay up to 5,000 eggs. The cycle is completed in 8 to 12 weeks, but under adverse conditions the eggs can remain dormant for up to three years, and the resistance of individuals to fasting can reach up to 18 months.

The tick of most interest in Chile is the Brown Dog Tick (Rhiphicephalus sanguineus, L), a species found all over the world, whose most common host is the dog. However, it can also bite cats and people.

The adult male has a flat body and measures 3 mm. It has reddish-brown legs, shield and mouthparts, and small spots on the back. When they feed, they do not increase much in size, unlike the females, which before feeding resemble the males in size, shape and colour, but, once full, the females reach up to 1.8 cm in length and 9 mm in width, and the abdomen acquires a grey colour. Ticks can act as vectors for various diseases, such as Lyme disease (Borrelia burgdorferi), present in the Northern Hemisphere.