The Harm and Control Methods of the Spruce Bark Beetle

The spruce bark beetle (Ips typographus Linnaeus) belongs to the order Coleoptera, family Scolytidae. In China it is distributed in Northeast China, Inner Mongolia, Sichuan, ** and other places, mainly damaging spruce and Korean pine, and is a destructive pest in some spruce forest areas.

Damage characteristics: it bores galleries between the phloem and sapwood of pine trees, and the galleries are compound longitudinal galleries. It can also directly attack healthy trees, and often occurs together with other bark beetles, causing trees to die in patches.

Morphological characteristics

Adult body length 4.0-5.5 mm, body dark brown, glossy, covered with brown hairs. The frons has rough granules, and the upper part of the mouthparts at the lower center of the frons has a large tumor-like protrusion. The center of the pronotum has rough wrinkles, and the rear half is smooth and without punctures. The rear half of the elytra is sloped, and each side of the declivity has 4 teeth, the third being button-shaped and the other three conical; the 4 teeth are separated individually, with the greatest distance between the 1st and 2nd teeth. The declivity is dull, as if coated with a layer of soap foam. The declivity is the same in both sexes.

Eggs are long oval, about 1.0 mm long and about 0.7 mm wide, milky white.

Larva body length 4.0-6.3 mm, body curved, with many wrinkles, covered with setae, milky white. Similar to the larch bark beetle.

Before eclosion, the mandibles and the tips of the forewings of the pupa turn brown. Milky white, with 2 spine-like protrusions at the end of the abdomen.

Occurrence pattern: in Northeast China, 1 generation occurs per year, overwintering as adults at the base of larch trunks or under the litter layer, and a few overwinter under the bark of dead saplings or in old galleries. The life history is not synchronized; they emerge from dormancy in mid-to-late May of the second year. Adults can lay eggs 1-2 days after invading the trunk. The egg stage lasts about 14 days, the larval stage about 22 days, and the pupal stage about 12 days. Newly emerged adults remain under the bark for nearly 1 month, up to a maximum of 2 months, before boring out through the emergence holes. Double galleries, the galleries are not very long, generally about 7 cm, and the adults in the galleries are generally 1 male to 3 females. There are more than 30 egg chambers, each with only 1 egg. Mature larvae build a pupal chamber at the end of the larval gallery. During the entire growing period, almost all developmental stages can be found. This insect likes ventilation and light, but does not like direct sunlight or extremely shaded environments, so its distribution on the trunk is mainly concentrated in the middle and lower parts; on larch it lives together with the larch eight-toothed bark beetle.

Control methods

(1) Agricultural control.

Create mixed forests, and combine with tending and cutting to enhance tree vigor; pay attention to forest sanitation, and remove pest-infested trees and wind-broken trees; under the premise of good sanitary conditions, cut small-diameter wood in mid-April, set trap logs to attract and kill the pest, and then carry out debarking treatment uniformly.

(2) Protect natural enemies such as ground beetles, parasitic wasps, and woodpeckers.

(3) Chemical control.

From late May to early July, during the peak period of adult flight and invasion, spray the branches and trunks of living standing trees with 200-fold dilution of 2.5% deltamethrin ointment or 500-fold dilution of 30% cypermethrin poisonous paste to control adults.

Commonly used pesticides: deltamethrin, cypermethrin.