Mites and Ticks, a group of invertebrates related to spiders. Mites are 1/64 inch to 1/8 inch (0.4 to 3 mm) in length; ticks are 1/8 inch to 1 1/8 inch (3 to 29 mm) in length. Some species of mites live on land, others in water. Some are agricultural pests, feeding on crops and the leaves of fruit trees. Some species carry disease-producing microorganisms; one species causes mange in vertebrates. Other species of mites are beneficial, preying on aphid eggs and nematode worms. Ticks live on land, primarily in woods and pastures. Ticks are bloodsucking parasites that can carry disease-producing microorganisms, which they transmit to mammals, birds, and reptiles through a bite in the skin.

TicksTicks are bloodsucking arachnid parasites known to carry and transmit diseases.

Most species of mites and ticks lay eggs, but in some species the young are born live. The mite usually lays its eggs in the wounds it makes in an animal's skin or on the outside of a plant. The females of some species lay their eggs on plant leaves in loose webs, which they spin with silk produced in glands near their mouths. Tick eggs are laid in masses on the ground. The eggs of mites and ticks develop into larvae, which have three pairs of legs.

The larvae develop into nymphs, which have four pairs of legs, and the nymphs develop into adults. The adult mite or tick has a saclike body, with no separation of head, thorax, and abdomen. Piercing mouthparts are adapted for sucking juices from plants and for penetrating skin.

When a mite or tick bites, its entire head is thrust into the wound. An anchoring structure below the jaws holds firmly to the wound. In the mite this structure is smooth, and the mite is easily brushed off. In the tick this structure is toothed; ticks can be removed from the skin with tweezers, but care must be taken to remove the entire tick, not just the exposed body.

MitesMites have piercing mouthparts for sucking juices from plants and for penetrating skin.

Among the common mites are the chigger (or jigger), itch mite, chicken mite, cheese mite, and the red spider mite, a garden pest. The dog tick and the wood tick are common ticks that suck blood from humans, dogs, rodents, and other mammals; these ticks can spread diseases such as Rocky Mountain spotted fever and tularemia. Ticks of the genus Ixodes, including the deer tick, carry Lyme disease, an inflammatory disease in humans. The Texas fever tick carries Texas fever, a disease of cattle. A genus of ticks called soft ticks transmits a disease called relapsing fever, which affects humans.

The sheep tick, or sheep ked, is not a tick, but a wingless fly that spreads trypanosomiasis (a form of sleeping sickness) and other diseases of sheep.The deer tick carries Lyme disease.

The deer tickThe deer tick carries Lyme disease.

The itch mite is Sarcoptes scabiei; chicken mite, Dermanyssus gallinae; cheese mite, Acarus siro; red spider mite, Tetranychus telarius; dog tick, Dermacentor variabilis; wood tick, D. andersoni; deer tick, Ixodes dammini; Texas fever tick, Boophilus annulatus. Soft ticks belong to the genus Ornithodoros. All belong to the order Acarina of the class Arachnida. The sheep tick is Melaphagus ovinus of the family Hippoboscidae, order Diptera.

What Is A Tick?

A tick is an arachnid. It is similar to a mite, only larger. In fact, you don’t need a magnifying glass to see most ticks.

All ticks are parasites. They feed on the blood of other animals. Most live in fields and woods. Ticks lie among fallen leaves or on plants that grow low to the ground. If an animal brushes against the plant, the tick will leap onto its body. The tick begins to suck the host’s blood until its own body blows up like a tiny balloon. Then the tick falls off and molts. It waits for a new host to pass by so it can have another meal.

Most ticks are harmless to animals and humans. But some spread diseases, such as Rocky Mountain spotted fever, Lyme disease, and relapsing fever.

The American dog tickThe American dog tick transmits Rocky Mountain spotted fever.
Which “Spider” Is Really A Mite?

Don’t let the red spider’s name confuse you. The red spider is really a mite. It just looks like a spider. And it is not always red. Red spider mites may also be green, yellow, or orange.

The red spider mite feeds on plants, which it sometimes destroys. The mite uses its sharp mouthparts to rip open leaf cells. This damages the leaves—and may cause the plant to die.

A red spider is about the size of a grain of salt. Because the mite is so small, it is often detected by the damage it causes.