Identification and Control Methods of the Box Tree Moth

The box tree moth Diaphania perspectalis (Walker), also known as the box tree black-margined pyralid moth, belongs to the order Lepidoptera, family Pyralidae.

[Distribution and damage]:

It is distributed in Shaanxi, Hebei, Jiangsu, Zhejiang, Shandong, Shanghai, Hubei, Hunan, Guangdong, Fujian, Jiangxi, Sichuan, Guizhou, Xizang and other places. It damages boxwood, littleleaf boxwood, Lushan boxwood, Korean boxwood, etc. The larvae often connect surrounding leaves with silk to form a temporary nest, in which they feed; when the infestation is severe, they eat all the leaves, causing the entire plant to die.

[Morphological characteristics]:

Adult: The whole body is covered with white scales and hairs, body length 20~30mm, wingspan 40~50mm. The prothorax, the base, anterior margin and outer margin of the forewing, the outer margin of the hindwing, and the end of the abdomen are covered with dark brown scales and hairs, hence the name black-margined pyralid moth. The antennae are filiform, brown, with more than a hundred segments, and can reach the end of the abdomen in length. The wing surface is semi-transparent, with a purplish-red sheen. There are 2 white spots in the median cell, 1 small and 1 crescent-shaped. Males and females are very easy to distinguish: the female has 2 frenulum bristles, a relatively thick and large abdomen, and no hair tuft at the end of the abdomen; the male has 1 frenulum bristle, a relatively slender abdomen, and a black hair tuft at the end of the abdomen.

Egg: Oblong, with a smooth bottom surface and a raised upper surface, length 1.5mm; light yellow-green when newly laid, dark brown near hatching.

Larva: Cylindrical, total length 42mm when mature; head dark brown, thorax and abdomen dark green, with glossy hair-bearing tubercles and sparse setae on the surface. The dorsal line is green, the subdorsal line and spiracular upper line are dark brown, the spiracular line is light yellow-green, the basal line and ventral basal line are pale cyan, the areas on both sides of the dorsal line are yellow-green, and the area between the subdorsal line and the spiracular upper line is pale cyan-gray.

Pupa: Fusiform, length 18~20mm. Emerald green when newly pupated, later pale cyan to white; wing buds and compound eyes dark brown to black. The posterior end of the body has 8 anal spines arranged in 1 row, with the tips curled into hooks.

Cocoon: The mature larva pupates in a cocoon; the cocoon is formed from silk binding leaves together, is oval, and 40mm long.

Life habits:

In Nantong, Jiangsu, 3 generations occur per year, and the larvae overwinter in nests formed by two host leaves. Overwintering-generation larvae begin to move and feed in late March. The pupal periods of the overwintering generation and the 1st and 2nd generations are 12~18 days, 6 days, and 7~11 days, respectively. The larvae generally have 6 instars, a few have 5 instars, and overwintering-generation larvae have 9~10 instars. After adult emergence, they mate at night and lay eggs the next day; eggs are mostly laid on the underside of leaves, with each female laying 153~222 eggs. After hatching, the larvae begin feeding after 5~12 hours and consume 80~100 leaves in their lifetime; during feeding they often connect surrounding leaves with silk to make a temporary nest. After the overwintering larvae make a nest, they molt and pupate within it.

[Control methods]:

① During the adult egg-laying period, check and remove egg masses once every 2~3 days; inspection is easier in the morning or evening when the sun shines obliquely. Taking advantage of the larvae's nesting habit during feeding and the overwintering pupae being in the insect nests, the collected eggs and nest pupae and cocoons can be burned promptly.

② During the larval damage period, spray 50% fenitrothion emulsion at 1000 times dilution, or 50% phoxim emulsion at 1000~1500 times dilution, or Bacillus thuringiensis var. aizawai? No. Use "killing borer bacteria" 200~400 times dilution.