Spider mites

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These pests are small 8 legged insects closely related to spiders. They are far more active in warmer climates and this is the reason why inside they mostly occur during spring and autumn. They seek refuge inside from the cold nights outside so they can effectively start their breeding cycle.

The type you are most likely to encounter will show damage by sucking sap from the leaves.

Although mites differ from insects in several ways, their damage to ornamental plants resembles that of thrips and lace bugs. Most mites have eight legs as adults (adult insects usually have six). Mites do not have wings (some adult insects have wings) but can be aerially dispersed by breezes and winds more or less like aerial plankton, particularly in hot, dry weather. It is thought the mouthparts (chelae) of mites evolved from legs with a prehensile joint, (the digitus mobilus) which allows the mite to chew with a vertical, scissors like action. In spider mites, broad mites, and cyclamen mites, the chelae have evolved into sharp mouthparts that mites use to pierce the surface of the plants they feed on in order to suck out the contents of the plant cells. Mites evidently inject saliva as they feed for one of the first symptoms of broad mite and cyclamen mite feeding is failure of the host plant to blossom. Infested plants then exhibit a variety of plant growth regulator symptoms including twisted and distorted growth, and shortened internodes and petioles.

The eight-legged adult can be pale green, greenish amber, or yellowish. Usually having two (sometimes four) black spots on top, the twospotted spider mite is about 0.4 mm long.

The spherical egg ranges from transparent and colorless to opaque straw yellow.

The six-legged larva is colorless, pale green, or yellow.

Similar to the adult except in size, the nymph has eight legs and is pale green to brownish green. Large black spots may develop on each side.

  Last modified: 21:57 - Feb 03, 2001  

faq:732 "Spider mites"