Saddle crab spider

One of the predatory pests of Chinese oak silkworm, mainly harming 1st-2nd instar Chinese oak silkworm larvae. It belongs to the family Thomisidae, order Araneae, with the scientific name Xysticus ephippiafus Simon. There are many species of spiders that harm Chinese oak silkworm, widely distributed, occurring in all Chinese oak silkworm rearing areas across the country. In Liaoning, China, 26 species of silkworm-damaging spiders have been found. Besides the saddle crab spider, the main species include Misumenops tricuspidatus, Philodromus spinitarsis, and Araneus cornutus.

Morphology: Among adult spiders, the female is 7-8 mm long, brown or light yellowish-brown, with dark brown longitudinal stripes on both sides of the dorsal cephalothorax; the center is light brown with a light brown line. The front edge of the cephalothorax has several black spines. The first and second pairs of walking legs are longer than the rear two pairs, thick and large, darker in color, with dark brown spots. The male is 4-5 mm long; the cephalothorax and abdomen are dark brown; the femora and patellae of the first and second pairs of walking legs are dark brown, while the other segments are light yellow, clearly different from the female. Eggs are oval, 0.9-1.0 mm long. First-instar spiderlings are 1.1-1.2 mm long, light yellow, with white walking legs and reddish-brown eyes. Sixth to seventh-instar spiderlings are 3.9-6.8 mm long, dark brown or blackish-brown; other colors and morphology are basically the same as the adult.

Habits: In Liaoning, China, there is one generation per year. It overwinters as adults, subadults and spiderlings in holes at the base of oak trees. Overwintering adults begin mating and laying eggs in mid-May of the following year; the female lays eggs 17-21 days after mating, with the peak egg-laying period from mid-June to mid-July. Lifespan is 25-114 days. Female adults can live more than 9 months. Adults are active from April to October, with the peak activity period from mid-June to early October.

Damage: The saddle crab spider can harm 1st-2nd instar silkworm larvae from May to October. One saddle crab spider can eat up to 4 first-instar Chinese oak silkworm larvae per day, averaging 1.7. During the peak occurrence period, an average of 65 spiders are found per 100 sq m.

Control: 10-15 days before young silkworms enter the rearing field, spray a 200-300 times water dilution of 10% chlordimeform emulsifiable concentrate in the field. On the ground of the rearing field, 1.5% phoxim powder can be sprayed; 7 days after application, silkworms can be placed on the oak trees. Natural enemies include ants, ichneumon wasps, nematodes, mites, and Beauveria bassiana.