The scientific name of this pest is *Gryllotalpa unispina* Saussure, belonging to the order Orthoptera and family Tettigoniidae. It is also known by several common names, including single hedgehog, big clam, lara clam, teriyao, earth dog, and ground dog. This species is primarily found north of 32°N latitude.
From April to November, it infests a wide range of crops such as cereals, tobacco, sweet potatoes, melons, and vegetables, feeding on seeds, seedlings, and young shoots. Its presence can significantly affect crop establishment and growth.
The damage caused by both adults and nymphs is severe. They burrow into the soil, damaging seeds, seedlings, and roots. Their tunneling disrupts the root systems, leading to dehydration and eventual death of the plants. In greenhouses, where temperatures are higher and conditions are more favorable, the damage tends to be even more intense.
Adult females measure 45–66 mm in length, while males are slightly smaller, ranging from 39–45 mm. The body is brown with a dark brown head, and the compound eyes are oval in shape. The antennae are long and thread-like. The thoracic shield is shield-shaped, with a heart-shaped red spot in the center. The forewings are yellowish-brown, flat, and cover less than half of the abdomen, while the hind wings are longer and rolled into a tube. The front legs are well-developed, and the hind legs have a distinct gap between the inner margins, distinguishing them from similar species like the Oriental Warts. The eggs are oval, measuring 1.6–1.8 mm, and vary in color from yellow-white to yellow-brown. There are 12 nymphal stages, with the early instars resembling the adults in shape and color.
The life cycle of *Gryllotalpa unispina* typically takes about three years to complete. In regions like Beijing, Shanxi, Henan, and Anhui, overwintering nymphs or adults become active in early spring, with adults beginning to lay eggs in June. Nymphs hatch in mid-to-late June and progress through several molts before entering their third year. By October and November, they reach the 8- to 9-year-old stage. In the following spring, they continue to develop, molting several times before becoming adults. After mating, females lay eggs in underground chambers, with each female producing an average of 288–368 eggs over a one-month period. Once the nymphs reach the third instar, adults become nocturnal and exhibit phototactic behavior.
To manage this pest, several control methods are recommended. First, applying fully decomposed organic fertilizer can reduce its population. Second, light traps can be used to capture adult insects. Third, when the density reaches 0.3–0.5 per square meter, it is considered moderate, and above 0.5 indicates a serious infestation requiring intervention. Poison baits, such as those made with trichlorfon, can be applied during sowing or when seedlings are present. For example, mixing 4–5 kg of bait per 667 m² with a 300-fold dilution of 90% trichlorfon solution and spreading it in the evening before irrigation can be effective. Soil treatments using insecticides like phoxim, parathion, or methyl isothiocyanate at appropriate concentrations are also useful. Additionally, granular formulations such as 6% Myda can be mixed with fine soil and applied at a rate of 5008 per 667 m². These measures help to minimize damage and protect crops effectively.
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