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The adult cricket, scientifically known as *Bradtsua idiruogaga* Yang et Zhang, is commonly referred to as the yellow-footed mosquito. This small black insect has a body length that is only one-fourth of the typical mosquitoes we encounter daily. Its peak activity occurs between 9 and 11 am, making it a significant pest in leek cultivation. It is found across various regions in China, including the northeast, north, northwest, and areas south of the Yangtze River such as Sichuan and Zhejiang. The primary host plants include leeks, onions, and garlic, all members of the lily family.
The eggs are laid in soil cracks, gaps between plants, and leaf sheath crevices—areas that are hard to detect with the naked eye. These egg masses measure approximately 0.38 mm in length and are oval in shape. The larvae tend to cluster around the bulbs of leek plants, causing damage to the stems, leaves, and bulbs, leading to yellowing and rotting. Despite their tiny size (only a few millimeters), these pests have strong feeding capabilities, and severe infestations can lead to dense root systems being targeted for control.
In terms of injury characteristics, adults lay eggs in soil cracks or clods near alfalfa. Once hatched, the larvae gather around the bulbs and tender stems of leeks, damaging young stems and causing leaves to turn brown and rot. In severe cases, the entire plant may be affected. The adult measures about 2.5 mm in length, with a dark brown body and a small head. The thoracic bulge protrudes forward, covering the head. Larvae are yellow-white, slender, and full, measuring up to 7 mm in length, with a black head and pointed tip. The pupal stage starts off yellowish-white, transitions to yellow-brown, and ends up grayish-black before emerging as an adult.
This pest typically has four generations per year, occurring in early May, mid-June, early August, and late September. During winter, from late July to early August, adult larvae emerge. They colonize the underground rhizomes of leeks. Both adult and larval stages are highly mobile and often reside in soil gaps around leeks. Mature larvae or pupae overwinter in the soil at depths of 3–4 cm. Adults avoid light, prefer humidity, and are attracted to the scent of onion and garlic. Eggs are laid in the soil around leeks, and larvae feed on underground leaf sheaths, tender stems, and buds, causing damage by biting stems and breaking into bulbs. In open fields, larvae are typically found 2–3 cm below the surface, rarely deeper than 5–6 cm. Soil moisture plays a key role in their occurrence, with clay soils having fewer infestations compared to sandy soils.
For control, several strategies are recommended. After harvest, covering the leek field with plastic film for 3–5 days helps trap adult insects due to the lingering leek odor. Transplant management includes using new soil, soaking seeds before sowing, and avoiding bulb transfer. Roots should be exposed for 1–2 days before planting to kill young pests. Sand coverage is another technique used to prevent "jumping roots," where roots rise above the soil and cannot absorb nutrients. Instead of traditional soil cover, sand is applied in layers of 1–3 cm to suppress egg-laying and improve conditions for pupae.
Chemical control involves watering and spraying during different growth stages. For open-field leeks, herbicides are applied 6–7 times, especially during March and September. Cold-shed and warm-shed leeks require specific timing for pesticide application, depending on the season and growth stage. Larval control uses products like 50% phoxim EC, 48% loessben EC, and 1.1% matrine powder. Adult control involves applying trichlorfon powder or pyrethroid-based sprays during peak emergence hours (9 am to 11 am). Soil surfaces around leeks are also sprayed to manage adult populations effectively.
In addition to chemical methods, agricultural, ecological, and physical controls are employed. Agricultural practices include proper transplanting, seedbed preparation, and crop rotation. Ecological methods involve using arch shelters to improve ventilation and reduce flea populations. Fertilization techniques focus on composting and avoiding raw manure to prevent pest breeding. Physical traps use sugar-vinegar solutions and electric lights to attract and capture adult insects.
By combining these approaches, farmers can significantly reduce pest damage while maintaining environmental sustainability and improving leek quality and yield.