The important sawflies that damage forest trees in China include the yellow-margined sawfly, the pine sawfly, the larch-billed sawfly, the spruce-billed sawfly and the helan-billed sawfly.

① Acantholyda flavomarginata Maa: The female body length is 12 to 16 mm.

The color spots on the head are shown in Figure 2a.

The antennae have 24 to 34 sections; the base is yellow, then gradually turns to dark brown, and the tip becomes dark brown; there is a black vertical stripe on the back of the stalk.

The legs are black, with a small part of each section being yellowish brown.

Lightly filmed leaves are brown-black.

The wings are leathery, transparent, light brown, with lavender iridescence, and the wing veins and wing moles are dark brown.

Male worms are 10 to 12 mm long.

The body color is slightly different from that of the female insect.

Distributed in Fujian, Jiangxi, Hunan, and Guangxi, China.

Harm the masson pine.

There is one generation a year or more, and the larvae overwinter in the soil.

The overwintering larvae begin to pupate in early February of the following year, and early March is the peak pupation period.

Adults begin to emerge in mid-February and begin laying eggs at the end of February.

The eggs are laid on the inside of pine needles, usually one egg per needle, and they like to be laid on short trees.

In early March, a new generation of larvae begins to hatch, build a nest along the branches or main tips, and live in it.

Generally, there is only one larvae in each nest, and insect droppings are rarely left in the silk nest.

After 3 years of age, the damage is more severe, feeding on both old and new needles.

Figure 2 The color spots on the head of the female sawfly a. The yellow-margined sawfly; b. The pine sawfly; c. The larch-billed sawfly; d. The spruce-billed sawfly; e. Helanthropus

Acantholyda posticalis Matsumura (Acantholyda posticalis Matsumura): Female body length is 13 to 15 mm.

The stain on the head is shown in Figure 2b.

Legs (except basal joints) and pale membrane leaves are red and yellow.

The antennae have 35 to 38 sections; the tips are smoke black, the handle sections are black, and the rest are red and yellow.

Male worms are 10 to 11 mm long.

Distributed in Shandong and Shanxi, China.

There is one generation per year, with mature larvae overwintering in earth chambers.

The overwintering larvae begin to pupate at the end of April and early May of the following year, and begin to emerge in mid-May. The peak emergence period is at the end of May and early June.

Eggs are laid on the underside of needles, first on old leaves, then on new leaves of the current year, and rarely on 3-year-old needles.

Early to mid-June is the peak spawning period.

The egg period lasts 15 to 17 days, and the peak hatching period is mid-June.

The newly hatched larvae spin silk and form a web at the base of the needles, live in it, bite off the needles and drag them back into the web to feed.

After 3 years of age, they move to the base of the new shoots of the current year and spin silk to make dense insect nests to settle.

The nest is cylindrical, with one insect living in each nest.

The larvae are frightened and quickly retreat into the nest, and have the habit of spinning silk and drooping.

③ Cephalcialariciphila (Wachtl): The female body length is 10 to 12 mm.

The stain on the head is shown in Figure 2c.

Most of the antennal handle segments and stalk segments are black from the back downward, the whip segments are dark brown, the more than ten segments at the ends are darker, and the 7th to 8th segments at the base are lighter in color.

Lightly filmed leaves are brown-black.

The male worm has a body length of 8 to 9 mm and an antennae of 23 to 25 segments.

Distributed in Shanxi, China.

Damage to North China larch.

In the Guanluishan forest area of ??Shanxi Province, there is one generation per year, and the mature larvae overwinter in the soil or between the soil and litter.

The overwintering larvae begin to pupate in mid-April of the following year. The peak period of pupation is at the end of April, and the peak emergence period of adults is in mid-to-late May.

Eggs are laid on the back of the ends of needles in the outer whorl of leaf clusters. One egg is laid on each needle, and each female lays more than 30 eggs.

The egg stage is about 30 days.

After the larvae hatch, they immediately crawl to the base of the leaf clusters and spin silk to make a nest, where they feed the next day.

The larval stage lasts 21 to 28 days.

The number of occurrences is generally greater on the southeast slope than on the northwest slope, and on the south side of the crown than on the north side.

④Cephalcia abietis Linnaeus: The female body length is 12 to 15 mm.

The stain on the head is shown in Figure 2d.

The rear and lower parts of the lateral corners of the pronotum, the wing bases, the triangular pattern at the rear end of the proscutellum, the majority of the rear part of the mesothorax and metathorax scutellum, and the front end of the prothorax and lateral segments are all yellow.

Both ends of the antennal shank segment, stalk segment, and whip segment are 2/3 of the length of the antennae. Except for the first segment, the tibia segment, tarsus segment, and the dorsal segment of the abdomen are all yellowish brown.

Light film leaves are red and yellow.

The front ends of the antennae, stalk segments, cephalothorax and the rest of the abdomen are all black.

The tentacles have 26 to 29 segments.

Male worms are 11 to 12 mm long.

Distributed in Inner Mongolia, China.

Damage red spruce.

There is one generation in one year or more, and the larvae and pre-pupas build earth chambers in the soil to survive the winter.

Pupation begins in early May of the following year, and emergence and egg laying begin in early June.

Eggs are mostly laid at the ends of current-year needles, arranged in rows.

The eggs begin to hatch in late June.

The larvae spin silk and form webs to feed, and begin to fall to the ground in late July, where they spend the winter in the soil.

⑤Cephalcia alashanica Gussakovskij: The female insect is 12 to 14 mm in length.

The stain on the head is shown in Figure 2e.

The antennae have 24 to 26 segments; the ends are smoky gray brown, the inner side of the stalk section is dark brown near the ventral surface, and the rest are dark yellowish brown.

Pale film leaves are dark brown.

Male worms are 10 to 11 mm long.

Distributed in Inner Mongolia, China.

Damage red spruce.

There is one generation a year or more, overwintering as larvae and pre-pupas.

The stages of occurrence of each insect state are roughly the same as those of the spruce sawfly.

Eggs are laid on 2- to 3-year-old leaves, arranged from base to end, 1 to 3 rows per leaf.

The newly hatched larvae swarm at the base of needles, spin silk and make a net of needles, and live in it to feed. The remaining needles and feces adhere to the net, and gradually become a nest.

Feed on old leaves before 3 years of age, and feed on young leaves later on.

Larvae of each instar crawl forward while spinning silk.