Acarina: mites and ticks

Characteristics
Mites and ticks belong to one of the most diverse group of all the arachnids and can range in size from minute up to 1 centimetre. Due to their diverse appearance a general description is difficult to give, however all have the following characteristics:

Halotydeus destructor (redlegged earth mite) Dung beetle infested with mites

• 4 pairs of legs, although some juveniles only have 3 pairs gaining a forth pair with their first moult
  
  
• No external segmentation of the abdomen, individuals appear as a single body mass
  
  
• Never have antennae

Life Cycle
Reproduction in mites and ticks is very variable with some species mating through the direct transfer of sperm via coupling of the genital regions. Other species transfer sperm indirectly with the male placing a sperm droplet on the genital opening of the female with his legs or chelicerae. After fertilisation the female will usually lay her eggs in the substrate where they are left to hatch. The first free-living stage is called a larva and has only 3 pairs of legs. After the first moult it will gain its fourth pair of legs and will moult several more times before becoming a mature adult.

Feeding
Most species of mites are predatory and will feed on a variety of small invertebrates, while others are more herbivorous and often feed on plant sap, sometimes causing damage to agricultural crops and garden plants. Ticks are adapted to feeding on the blood of vertebrate animals such as humans, dogs or livestock.

Habitat
Mites are found in almost all habitat types including terrestrial, freshwater and marine environments. Terrestrial mites are commonly found in soil or leaf litter, under the bark of trees or feeding on the leaves and stems of plants. Both mites and ticks can be found living as parasites of other invertebrate and vertebrate animals. Most ticks are only discovered after they have attached themselves to a host animal.