How to check for silkworm diseases? Learn the seven-observation diagnostic method

Observe development: Healthy silkworms develop and grow uniformly. If the body is enlarged, develops too fast, and the instar period is noticeably shortened, be alert for silkworm nuclear polyhedrosis. If the body is too thin and uneven in size, be alert for silkworm empty-head disease, stings by golden haired caterpillars, and exhaust gas poisoning.

Observe feeding on mulberry: Large silkworms make sound when eating mulberry leaves; if the sound is faint or absent, be alert that the silkworms are sick. With pesticide poisoning, silkworms will crawl about wildly and gradually stop feeding and spit out milky silk.

Observe behavior: Healthy silkworms are lively in behavior, highly alert, and quick to respond. Unhealthy silkworms react abnormally. For example: (1) Silkworms with nuclear polyhedrosis crawl about frantically and often crawl out of the rearing bed. (2) Sick silkworms that cluster together, feed poorly, and twitch their heads and thoraxes usually have acute pesticide poisoning or flacherie. (3) Slow crawling and sluggish responses are symptoms of gastrointestinal-type nuclear polyhedrosis, viral soft rot, and white muscardine.

Observe body color: Silkworms with nuclear polyhedrosis and green muscardine appear milky white and shiny, and their bodies rupture easily, discharging pus. Silkworms with flacherie have empty thoraxes and tails, with a slightly yellowish-brown color on the rear dorsum; this is a specific symptom. Before and after mounting on the cocooning frame, if large dark purplish-brown silkworms appear, it is caused by @#@261@#@ burrowing into the silkworm body. After the bodies of silkworms with white muscardine and yellow muscardine stiffen, a peach-red color first appears at the tail, then gradually spreads over the whole body.

Observe body form: If the segments or intersegmental membranes of silkworms are swollen, be alert for nuclear polyhedrosis, green muscardine, and poisoning. The corpses of silkworms with septicemia first stiffen, then soften, and rot quickly. The corpses of silkworms with muscardine gradually harden.

Observe vomit: Poisoning causes copious vomiting. Silkworms that vomit a small amount of gastric juice, often hanging at the mouthparts, have muscardine or flacherie.

Observe feces: Silkworms with gastrointestinal-type nuclear polyhedrosis, viral soft rot, or bacterial gastroenteritis pass soft feces, watery feces, or even water-like feces. These sick silkworms and silkworms poisoned by organophosphorus pesticides all pass unformed feces.