What are Two-Spotted Spider Mites?
Two-spotted spider mites (TSPM) are a group of arachnids found worldwide. They have been known since the late 1800’s, but their exact origin is still unknown. These spiders were first described from Europe and North America, but they spread rapidly throughout the world due to human activity such as deforestation, urbanization and agriculture. TSPM was discovered in Australia in 1999. There are many species of these spiders, with over 100 identified so far. They range in size from less than 1 mm to up to 30 cm long. Their body color varies from yellowish brown or grayish white, sometimes with black spots. Males tend to be larger than females and are often seen crawling along walls and ceilings. Females are smaller than males, but they do not appear to mate until they reach a certain size. They have eight legs and four eyes. Most species of tarantulas are capable of killing them, however some species may only cause minor symptoms such as redness or itching at the bite site.
The two-spotted spider mite lives in warm climates where there is little sunlight and it breeds under rocks and debris in soil or woodpiles. There it lays eggs, which hatch into spiderlings after about 10 days. As with most arachnids, they molt several times before becoming adults capable of reproduction. Spider mites are related to ticks, scorpions and other mites.
They do not have wings and cannot fly or jump. They can only crawl, but they can move very quickly. Spider mites are usually green or red, but they may also be yellowish, brown or purple in color. They have 4 pairs of legs and usually have long, slender front legs. They have small bodies compared to their legs and they have no wings or antennae.
Spider Mites and Plants
TSPM are very small arachnids with a host of different species. They appear like tiny spiders and are closely related to red spiders, which feed on plants. They have mouth parts designed to pierce the plant’s cells and suck out the cell sap. They leave a trail of webbing as they move around the plant, which some people mistake for signs of other pests such as webbing clothes moths.
They can cause leaves to turn yellow and stunt the plant’s growth. They leave a sticky residue on the surface of plants that can be a good culture medium for mold. This also makes them difficult to see without the help of a magnifying glass or a hand lens.
Sources & references used in this article:
Biological control of two-spotted spider mites using phytoseiid predators by MW Sabelis – 1982 – library.wur.nl
Suppression of two-spotted spider mite (Tetranychus urticae), mealy bug (Pseudococcus sp) and aphid (Myzus persicae) populations and damage by vermicomposts by NQ Arancon, CA Edwards, EN Yardim, TJ Oliver… – Crop Protection, 2007 – Elsevier
Allocating time between feeding, resting and moving by the two-spotted spider mite, Tetranychus urticae and its predator Phytoseiulus persimilis by JS Bancroft, DC Margolies – Experimental & applied acarology, 1996 – Springer
Toxicity of quinones against two-spotted spider mite and three species of aphids in laboratory and greenhouse conditions by Y Akhtar, MB Isman, CH Lee, SG Lee… – Industrial Crops and …, 2012 – Elsevier
Characterizing indices of damage to tomato by the two- spotted spider mite, Tetranychus urticae Koch (Acari; Tetranychidae) to achieve biological control by P Nihoul, G Van Impe, T Hance – Journal of Horticultural Science, 1991 – Taylor & Francis
The effectiveness of various pesticides against resistant two-spotted spider mites on greenhouse roses by WW Allen, AK Ota, RD Gehring – Journal of Economic …, 1964 – academic.oup.com
Biological control of the two-spotted spider mite on strawberry in southern California by ER Oatman, JA McMurtry – Journal of economic entomology, 1966 – academic.oup.com
Ultrastructural changes in strawberry leaves infested by two‐spotted spider mites by M Kielkiewicz – Entomologia experimentalis et applicata, 1985 – Wiley Online Library