What’s a Saddle Crab Spider

One of the predatory pests of tussah, mainly damages the 1 to 2 instar tussah. It belongs to Xysticus ephippiafus Simon and belongs to the order of the spider spider family. There are many types of spiders that damage tussah silkworms, and they are widely distributed. Twenty-six species of silkworm spiders have been found in Liaoning. In addition to the saddle-shaped crab spiders, there are also three-headed flower spiders, tarsal spiders, and shoulder round spiders.

Morphology

The female body of the adult spider is 7-8 mm long, brown or light yellowish brown, with dark brown vertical stripes on both sides of the back of the head and chest; the center is light brown with a light brown line. Two rows of 8 eyes, both concave back. The side ridges are separated from each other. Around the front eye and the side eye mounds are white. There are several black spines on the front edge of the cephalothorax. The first and second pairs of steps are longer and thicker than the latter two pairs, with darker brown spots. The abdomen is long ovoid, the back is wider than the front, the back of the abdomen is brown, with horizontal stripes, and the periphery is light yellow. The male spider has a body length of 4 to 5 mm. The head, chest and abdomen are dark brown. The legs and knees of the first and second pairs of feet are dark brown, and the other sections are light yellow, which is obviously different from the female spider. The eggs are oval, 0.9-1.0 mm in length, milky white at first birth, and light yellow later. If the spider is divided into 7 years, the morphology of each instar is very different. The 1st-year-old spider has a body length of 1.1 to 1.2 mm, a pale yellow body, white feet and reddish brown eyes. The body length of 6 to 7 instar spiders is 3.9 to 6.8 mm, the body is dark brown or dark brown, and other colors and shapes are basically the same as adults.

Habits

The saddle crab spiders live in Liaoning for one generation a year. Adult spiders, subcheng spiders and Ruo spiders live through the winter in the caves at the roots of oak trees. Overwintering adult spiders begin to mate and lay eggs in mid-May of the following year. Female spiders lay their eggs 17-21 days after mating. The peak period of egg-laying is from mid-June to mid-July. Eggs are laid on tussah leaves or hazel leaves in the tussah sericulture farm. Before laying eggs, silk is spun to stick the leaf edges together to form a bag-shaped egg chamber (egg bag). The eggs are laid in the egg chamber. 1 female spider The average number of eggs laid is 150. The eggs hatch in 8-11 days. The first-year-old spider grows and develops in the egg bag, and the second-year-old spider drills out of the egg bag and climbs to the tree to disperse and live independently. The female spider is 7 years old, 133 days in total, and becomes an adult spider after 7 molting (8 years old). If spiders occur from mid-June to mid-October, mid-July is the peak period. A few adult spiders appeared in mid-to-late October, and began to overwinter in late October. This kind of spider is a game spider, which preys on young insects. After March, they usually live on 1 to 3 year old oak trees or dwarf shrubs. At the same time, they also like to live in places with dense vegetation leeward and sunny. Spiders are active during the day and hunt prey. Activities are frequent when the temperature is high, and they don’t like activities on rainy or windy days. The adult lifespan of the saddle crab spider is 25 to 144 days. Adult female spiders can live for more than 9 months. The spider activity period is from April to October, and the peak period is from mid-June to early October.

Harms

The saddle crab spider can injure 1 to 2 instar young silkworms from May to October. A saddle-shaped flower crab spider can eat up to 4 first-instar tussah silkworms per day, with an average of 1.7. In the peak period, an average of 65 spiders were found per 100 square meters.

Controlling

Young silkworms 10-15 days before entering the silkworm farm, you can spray 200-300 times aqueous solution of 10% insecticide essence emulsion in the silkworm farm. 1.5% phoxim powder can be sprayed on the silkworm grounds, and silkworms can be placed on the tussah within 7 days after spraying. Natural enemies include ants, bees, nematodes, mites, and Beauveria bassiana.