Boxwood silk borer
The scientific name of Diphania perspetalis Walker, also known as boxwood silk borer, boxwood black-edged borer moth, lepidoptera borer moth family, in addition to harming small-leaf boxwood, but also endangers large-leaf boxwood, wei spear and other garden plants, is one of the important leaf-eating pests of small-leaf boxwood.
1. Hazard characteristics
The larvae feed on plant leaves, spit silk as a nest, and often conjugate several leaves with silk, curl into a nest, and the nest grows as the larvae grow. In severe cases, all the leaves are eaten, resulting in dead branches or even the death of the whole plant, which seriously affects plant growth and landscape. In recent years, the harm in various parts of the country has been increasing year by year.
2. Morphological characteristics
Adults: 14 mm to 19 mm body length, wingspan 33 mm to 45 mm; dark brown head, white scales between the antennae of the head, brown antennae; light brown thorax and abdomen, brown scales on the thorax, dark brown at the end of the abdomen; white translucent wings with purple flashes, the leading edge of the forewings is brown, there are two white spots in the middle chamber, one is small, the other is curved into a crescent, the outer and posterior edges have a brown band, and the outer edge of the hindwings is dark brown.
Eggs: Oval, 0.8 mm to 1.2 mm long, white to milky white at first birth, pale brown before hatching.
Larvae: 42 mm to 60 mm long and 3.7 mm to 4.5 mm head width when mature; milky white at first hatching, blackish brown on the anterior pupae, yellowish green carcass, glossy hairs and sparse burrs on the surface, large dark spots on the front of the chest and dorsal mask, triangular, two pieces; green dorsal line, sub-dorsal line and valve line black-brown, valve line pale yellowish-green, baseline and ventral line pale bluish gray; pectoral foot dark yellow, gastropod pale yellowish green.
Pupae: spindle-shaped, tan, 24 mm to 26 mm long and 6 mm to 8 mm wide; 6 rump spines at the tail end of the abdomen, cocooned with silky leaves, cocoons 25 mm to 27 mm long.
3. Occurrence law
Yellow poplar silkworm wild borer occurs in two generations a year in the North China Petroleum Mining Area of Renqiu City, Hebei Province, and overwinters with young larvae in thin cocoons in the leaves of boxwood. Around mid-April of the following year, the overwintering larvae come out to feed, and at the end of May the mature larvae pupate in the leaves, and adults appear in mid-June. Adults are phototropic. Adults mostly feather in the evening, mating the next day, laying eggs on the 2nd day after mating, and the eggs are mostly laid on the back of the leaves or branches, many in blocks, and a few are scattered. Adults lie out at night, often inhabit shades during the day, fly away quickly when disturbed, and come out at night to copulate and lay eggs, with phototropism. After the larva hatches, they disperse to look for young leaves for food, and the hatching larvae eat leaf flesh on the back of the leaves. 2nd to 3rd instar larvae spit silk to connect the leaves and young branches into a nest, and eat the leaves internally, showing a lack of carving. After the 3rd age, the feeding range expands, the amount of food increases, the harm is aggravated, and only the silk mesh, insect skin and insect feces remain in the severely damaged plants, and a small amount of leaf edges and leaf margins remain. After 4 years of age, it is transferred to the pest, and immediately hides in the nest when it encounters an alarm, and after aging, it spits silk and conjugates the leaves as a cocoon pupa. The first generation of larvae occurs from mid-June to late July, and the second generation of larvae occurs from early July to early September.
4. Prevention and control methods
(1) Removing dead branches and leaves in winter and destroying the cocoons of overwintering insects can effectively reduce the source of insects in the second year.
(2) Using its nesting habit, the nest is removed in time at the young age stage of the first generation, and the pupal cocoon is removed at the pupal stage and destroyed in a centralized manner, which can alleviate the insect infestation that year.
(3) Use the phototropism of adult insects to trap, and set up black light lamps for booby traps during the occurrence of adult insects.
(4) Pharmaceutical control: The key stage of control is the stinging stage of overwintering larvae and the young age stage of the first generation of larvae, which can be controlled by 20% rapid killing butadiene emulsion 2000 to 3000 times liquid, 2.5% enemy killing emulsion 2000 to 2500 times liquid, 50% octyl thiophosphate emulsion 1000 to 1500 times liquid, 20% chrysanthemum emulsion 1000 to 1500 times liquid.
Some low-toxicity, non-polluting pesticides and biopesticides can also be used, such as Bt wettable powder with a content of 16000 IU/mg 500 to 700 times liquid, 1.2% bitter smoke emulsion 800 to 1000 times liquid, 25% urea suspension 1500 to 2000 times liquid, 20% rice full suspension 1500 to 2000 times liquid, etc.
(5) Protection of natural enemies: Protect parasitic concave-eyed wasps, jumping wasps, white zombie bacteria and parasitic flies.