FACTS ABOUT SPIDER MITES
Spider Mites and Web Spanning Open Space Between 2 Leaves of a Plant
Spider Mite Web and Infestation on Dying Leaves
Infestation of Twospotted Spider Mites on Webbing Surrounding a Plant
Twospotted Red Spider Mite
Sixspotted Spider Mite - Eotetranychus sexmaculatus
Twospotted Red Spider Mite - Tetranychus urticae
Sixspotted Spider Mites - Eotetranychus sexmaculatus
Banks Grass Mite - Oligonychus pratensis
Twospotted Spider Mite - Tetranychus urticae
Red Twospotted Spider Mite - Tetranychus urticae
Twospotted Spider Mites - Tetranychus urticae
Twospotted Spider Mite Adult Females with Hatchling and Many Eggs- Tetranychus urticae
Twospotted Spider Mite Infestation on a Leaf - Tetranychus urticae
Close up of Twospotted Spider Mites with Egg - Tetranychus urticae
Red Spider Mite Infestation
Close up of Red Spider Mite Infestation with Web and Eggs
Red Spider Mite - Tetranychus urticae
Red Twospotted Spider Mite with Silk Threads - Tetranychus urticae
Twospotted Spider Mites - Tetranychus urticae
Twospotted Adult Spider Mites with Egg - Tetranychus urticae
Red Twospotted Spider Mites
Sider Mites Spinning Web Between Stems of Leaves
Spider mites are members of the Acari (mite) family Tetranychidae, which includes about 1,200 species. They generally live on the undersides of leaves of plants, where they may spin protective silk webs, and they can cause damage by puncturing the plant cells to feed. Spider mites are known to feed on several hundred species of plants.
Spider mites are less than 1 mm (0.04 in) in size and vary in color. They lay small, spherical, initially transparent eggs and many species spin silk webbing to help protect the colony from predators; they get the “spider” part of their common name from this webbing.
Hot, dry conditions are often associated with population build-up of spider mites. Under optimal conditions (approximately 80 °F or 27 °C), the two-spotted spider mite can hatch in as little as 3 days, and become sexually mature in as little as 5 days. One female can lay up to 20 eggs per day and can live for 2 to 4 weeks, laying hundreds of eggs. This accelerated reproductive rate allows spider mite populations to adapt quickly to resist pesticides, so chemical control methods can become somewhat ineffectual when the same pesticide is used over a prolonged period.
Spider mites, like hymenopterans and some scale insects, are arrhenotochous: females are diploid and males are haploid. When mated, females avoid the fecundation of some eggs to produce males. Fertilized eggs produce diploid females. Unmated, unfertilized females still lay eggs that originate exclusively haploid males. The best known member of the group is Tetranychus urticae, which has a cosmopolitan distribution, and attacks a wide range of plants, including peppers, tomatoes, potatoes, beans, corn, cannabis, and strawberries. Other species which can be important pests of commercial plants include Panonychus ulmi (fruit tree red spider mite) and Panonychus citri (citrus red mite).
[Source: Wikipedia (https://en.wikipedia.org/wiki/Spider_mite)]
The body of a spider mite is separated into two distinct parts: (1) the gnathosoma and (2) the idiosoma. The gnathosoma includes only the mouthparts. The idiosoma is the remainder of the body and parallels the head, thorax and abdomen of insects. After hatching from the egg, the first immature stage (larva) has three pair of legs. The following nymphal stages and the adult have four pairs of legs.
The twospotted spider mite was originally described from European specimens. It is considered to be a temperate zone species, but it is also found in the subtropical regions. It is found throughout the USA in greenhouses where it survives the winters beyond its natural limits. Tuttle and Baker (1968) report this species to be found on deciduous fruit trees in northern regions of the U.S. and Europe.
The twospotted spider mite is oval in shape, about 1/50 inch long and may be brown or orange-red, but a green, greenish-yellow or an almost translucent color is the most common. The female is about 0.4 mm in length with an elliptical body that bears 12 pairs of dorsal setae. Overwintering females are orange to orange-red. The body contents (large dark spots) are often visible through the transparent body wall. Since the spots are accumulation of body wastes, newly molted mites may lack the spots. The male is elliptical with the caudal end tapering and smaller than the female. The axis of knob of aedeagus is parallel or forming a small angle with axis of shaft.
Spider mite development differs somewhat between species, but a typical life cycle is as follows. The eggs are attached to fine silk webbing and hatch in approximately three days. The life cycle is composed of the egg, the larva, two nymphal stages (protonymph and deutonymph) and the adult. The length of time from egg to adult varies greatly depending on temperature. Under optimum conditions (approximately 80ºF), spider mites complete their development in five to twenty days. There are many overlapping generations per year. The adult female lives two to four weeks and is capable of laying several hundred eggs during her life.
All mites have needle-like piercing-sucking mouthparts. Spider mites feed by penetrating the plant tissue with their mouthparts and are found primarily on the underside of the leaf. All spider mites spin fine strands of webbing on the host plant — hence their name.
The mites feeding causes graying or yellowing of the leaves. Necrotic spots occur in the advanced stages of leaf damage. Mite damage to the open flower causes a browning and withering of the petals that resembles spray burn.
When twospotted spider mites remove the sap, the mesophyll tissue collapses and a small chlorotic spot forms at each feeding site. It is estimated that 18 to 22 cells are destroyed per minute. Continued feeding causes a stippled-bleached effect and later, the leaves turn yellow, gray or bronze. Complete defoliation may occur if the mites are not controlled.
Spider mites are the most common mites attacking woody plants and the twospotted spider mite is considered to be one of the most economically important spider mites. This mite has been reported infesting over 200 species of plants.
Some of the more common ornamental plants attacked include arborvitae, azalea, camellia, citrus, evergreens, hollies, ligustrum, pittosporum, pyracantha, rose, and viburnum. The mite is also a pest of trees and may damage maple, elm, redbud and has been reported on ash black locust and popular. It has been occasionally found on other trees (Johnson 1991).
Fruit crops attacked include blackberries, blueberries and strawberries.
A number of vegetable crops such as tomatoes, squash, eggplant, cucumber are also subject to twospotted spider mite infestations and damage.
The twospotted spider mite is also a serious pest in greenhouses as well as on field grown chrysanthemums.