HOUSE DUST MITES
Dermataphagoides
 

GENERAL CLASS DESCRIPTION

More than 30,000 species of mites have been identified. They are placed in the arachnid order Acarina. Many new mite species (which includes ticks), are found and described every year. They have sack-like bodies, rather than segmented bodies like scorpions. Unlike spiders which have a combined head and thorax where the legs attach and an abdomen that is connected behind, mites have only a single (one part), oval body with legs attached to its sides. All first stage mite larvae have only six legs; both later stages, nymphs and adults, have eight. Most are the size of sesame seed.  Mites are more diverse than spiders; they are found all over the world from deserts to rain forests, mountaintops to tundra, salt water ocean floors to freshwater lakes. They suck plant juices and animal blood, make tumors (galls) in plants, and transmit diseases.

Mouthparts are attached at the very front end of a mite's body. These mouthparts consist of a group of small appendages that sometimes look like a head but the brain actually is located behind the mouthparts and eyes. The mouthparts of mites form a tube that ingest plant or animal juices. Very short appendages on either side of the mouthparts guide other mouthparts as they are inserted into food tissues. As the mite sucks, digestive juices gush out of the front of the body, mix with the food juices in the mouth, and are sucked back through the mouth tube. The mite's genital opening is found underneath and between the attachments of the first two pairs of legs.

Mites walk by using body muscles to press blood into individual legs. The movement of blood extends into individual legs. The movement of blood extends a leg out or forward. Little muscles in each leg segment, then pull the segment back, and the mite moves forward. Many mites use their first pair of legs like antennae, feeling in front as they walk along. Leg hairs have diverse purpose: some sense touch; others pick up odors; not uncommonly, some hairs have light-sensing cells which allow the mite to distinguish light from dark.
 

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