Identification and Control Methods of the Spruce Tortrix Moth

The spruce tortrix moth [Archipsoporanus (Linnaeus)], also known as the pine bud tortrix and the pine thick tortrix, belongs to the order Lepidoptera, family Tortricidae. In China it is distributed in Heilongjiang, Liaoning, Central China, South China and other places, and can damage slash pine, loblolly pine, masson pine, Korean pine, spruce and Chinese juniper.

Damage characteristics: the larvae bore into axillary buds, flower buds and male flowers, and gnaw on needles, affecting tree growth and seed yield.

Morphological characteristics

Adult body length 10-12mm, wingspan 22-30mm. The head and prothorax of the male moth are reddish brown, and the abdomen is brown; the forewings of the female moth are yellowish brown, with many brown markings.

Eggs are flat and oval, about 0.96mm long, milky white when first laid, gradually turning yellow. Egg masses are arranged in scale-like clusters.

Larvae are 20mm long, light green, with a dark brown head; the pronotal shield is orange with dark brown edges, and the suranal plate is light yellow.

Pupae are 15-16mm long, yellow-green when first pupated, gradually turning brown later. There are 8 anal spines, with strongly curled tips.

Occurrence pattern: 1-2 generations over five years in Northeast China, 2-3 generations in Zhejiang, overwintering as 2nd-3rd instar larvae spinning silk and attaching to axillary buds on branches and trunks. In late March to early April of the following year they begin to move and feed, often eating flower buds into oval depressions, then continuing to feed on male cones; when feeding on needles, they often spin silk to tie several needle bundles together and glue the middle part to the branches and trunk, feeding on the inner needles there, with a large leaf consumption, and often moving to new sites to cause damage. In late April the larvae spin silk to connect 3-5 male cone clusters into 1 bundle, and pupate inside, or pupate in the damaged needles. The pupal stage lasts 5-10 days, and adults emerge in early May. The 2nd generation adults appear in mid to late August.

Adults rest quietly during the day, mate that night, and are phototactic. Eggs are mostly laid on the bark surface of the trunk, with each female moth laying 205-410 eggs. Newly hatched larvae are good at crawling and have the habit of spinning silk and hanging down. Larvae have 4 instars, with a duration of 20-25 days.

Control methods

(1) Agricultural control.

Create mixed forests, strengthen tending, enhance tree vigor, and reduce damage; in combination with seed collection, prune off tied axillary buds to reduce overwintering sources of the pest.

(2) Black light trapping and killing.

(3) Chemical control.

During the larval stage, spray 90% crystalline trichlorfon and 40% dimethoate 2000-3000 times dilution, and 50% dichlorvos emulsifiable concentrate 1000 times dilution; the control effect can reach 95%.

Commonly used pesticides: trichlorfon, dimethoate, dichlorvos.