Scientific name: Atypena (= Callitrichia) formosana (Oi)
Common name: Dwarf spider
Leafhoppers and planthoppers.
Dwarf spiders are very small and are often confused with spiderlings of other species. They measure 1 to 5 mm in dimension. Their eyes are arranged in two distinct rows.
The adults have three pairs of spots or gray markings on the dorsal part of the spherical abdomen. Their tarsi are three-clawed. The males have normal chelicerae.
The eggs of A. formosana are globular.
Biology and ecology
Dwarf spiders are found in groups of 30 to 40 at the base of the rice plant. A female produces 80 to 100 spiderlings in her life span of 45 to 60 days. The eggs, covered with a thin layer of silk, are laid in masses on dried leaf sheaths. They do not receive any maternal care.
A. formosana prefers wetland habitats. It builds webs within the base of rice tillers above the water line and catches most of its prey in webs. It can also hunt directly and feed on 4 to 5 leafhopper and planthopper nymphs a day.
Barrion AT, Litsinger JA. 1994. Taxonomy of rice insect pests and their arthropod parasites and predators. In: Biology and management of rice insects. Manila (Philippines): International Rice Research Institute. p 13-362.
Shepard BM, Barrion AT, Litsinger JA. 1987. Helpful insects, spiders, and pathogens. Manila (Philippines): International Rice Research Institute. 127 p.