Spruce Monochamus alternatus

Spruce longicorn beetle (MonochamusurussoviFisher), alias spruce longicorn beetle, belongs to Coleoptera longicorn beetles, which is distributed in Northeast China, Inner Mongolia, Hebei, Shandong, Jiangsu, Shaanxi and other places. It is mainly harmful to red spruce, fish-scale spruce, stinky fir and so on.

The larvae cut down fallen trees, weak standing trees, wind fallen trees and logs in the timber yard, forming coarse insect paths, and adults gnawed on the young bark of live trees.

Morphological characteristics

The adult is 21-33mm in body length. Black body with dark green or bronze luster. The antennae of males are about 2-3.5 times longer than that of females, and the antennae of females are slightly longer than those of females. There are 3 inobvious tumor-like processes in the anterior thoracic dorsal plate, and the lateral thorns are well developed. Small shield densely covered with grayish yellow short hairs. The base of the sheath wing is densely grained and there are sparse short villi, the more toward the end of the sheath wing, the engraving point is flattened, the hair is denser, the end is all covered with villi, showing a yellowish color, and there is a transverse indentation in 3 places in front of the sheath wing. The base of the male sheath wing is the widest and widens backward. The female sheath wings are nearly parallel on both sides, and there are gray-white hair spots in the middle, which are clustered into 4 pieces, but there are often irregular changes.

Ovoid, 4. 5-5mm in length and 1. 2-1.5mm in width, yellowish white.

The mature larvae are 37-50mm in body length, 3-5.9mm in head shell width and milky yellow. The head is rectangular and the back end is round. About 2pm 3 shrinks into the chest. The forechest is the most developed, the length of which is the sum of the other two thoracic segments, and there are convex reddish-brown spots on the dorsal plate of the forechest. There are two transverse grooves on the back and ventral side of the chest and abdomen, two transverse grooves on the dorsal vesicular process, a circular groove on both ends of the transverse sulcus, a transverse groove on the abdominal step vesicular process, and a backward short oblique groove at both ends of the transverse groove.

The pupa is 25-34mm long, white to milky yellow, with well-developed lateral spines in the dorsal plate of the chest and 9 nodes in the abdomen.

The occurrence regularity is generally 1 generation in 2 years or 1 generation a year in Daxinganling forest region of Inner Mongolia, overwintering with larvae of large and small size. The adults began to Eclosion in early June, the spawning period was from late June to early September, and the spawning period was from late July to early August. The larvae began to hatch and ate phloem and sapwood surface under the bark, and the injured part was irregular. After about a month, the larvae began to build a vertical tunnel into the woody part and drill into the tunnel to overwinter at the end of September. In May of the following year, it drilled out of the xylem to feed on the phloem, and in the middle of July, the larvae matured, drilled into the xylem again to build a tunnel, and made a pupa chamber at the end of the tunnel. The larvae have 6 instars. The mature larvae overwintered again in the pupa chamber and pupated in the first ten days of May of the third year. After Eclosion, the adults remain in the pupa chamber in the trunk for about one week, and then drill out of the Eclosion hole, which is about 8mm in diameter.

Adults must be supplemented with nutrition, otherwise they can not reproduce, so there are a large number of spruce longicorn beetle adults in the crown of spruce trees during a large number of Eclosion. The female begins to lay eggs 10-21 days after Eclosion. After mating, the female finds a suitable trunk, starts to bite a zigzag groove, and then turns around to insert the ovipositor, laying 1-2 eggs at a time, laying 14-58 eggs in a lifetime, with an average of about 30 eggs. There are three kinds of tunnels in the xylem: horseshoe shape, arc shape and linear shape. It is thought that it is mainly harmful to fallen and weak trees, and it can also harm twigs, especially spruce needles, when replenishing nutrients in the adult stage.

Prevention and cure method

(1) strict quarantine shall be carried out and the spread and spread of log and wood with insects shall be strictly prohibited.

(2) strengthen the management of forest area.

Build mixed forest, strengthen tending, enhance tree potential; wood cutting is carried out during the inactive period of adults, and logs should be transported out of the forest in time in summer; logs in the lumber yard should be peeled in time to reduce the suitable host of longicorn beetles.

(3) protect natural enemies such as velvet armour and woodpeckers.

(4) Pesticide control.

When ① occurs in a small area, it can be prevented and treated by injecting Hercules and other drugs with strong internal absorption by punching machine.

The adult stage of ② longicorn beetles, especially during the peak period of Eclosion, is mainly used to spray the crown and trunk of the host tree when it is sprayed dry or replenished.

The pest wood of ③ should be treated in time. It can be fumigated with aluminum phosphide or methyl bromide, or sprayed from the top and both ends of the pile with green Villei.

④ was poisoned by spraying parathion, fenitrothion, malathion or deltamethrin in the active period of longicorn beetle adults in case of water, drought, fire and poor growth of large trees.

Commonly used agents such as fenthion, fenitrothion, malathion, deltamethrin, green Weilei, aluminum phosphide, methyl bromide.