Lepidopteran pests are highly destructive; common species include the rice leaf folder, beet armyworm, tobacco cutworm (cluster caterpillar), peach fruit moth, cotton bollworm, diamondback moth, melon worm, and legume pod borer. Once severe resistance develops, it causes significant losses and frustration for farmers, while also driving up pest control costs.

What are some examples of Lepidopteran pests?

Brown-banded tea tortrix, brown stinging caterpillar, coffee leopard moth, cluster caterpillar (tobacco cutworm), flat nettle caterpillar, large bagworm moth, tea bagworm, tobacco budworm, tung-oil tree looper, yellow stinging moth, yellowish tea tortrix.

The difficulty in controlling them stems primarily from the following characteristics:

1. High reproductive capacity

The cabbage white butterfly caterpillar (*Pieris rapae*) produces 11–12 generations per year, with outbreak periods occurring from March to June and September to November, making them hard to control. The beet armyworm (*Spodoptera exigua*) goes through 6–8 generations annually; outbreaks are frequent in July and August—and even more severe during hot, dry years—with the generation cycle shortening further under optimal temperatures.

2. Small body size

They easily hide in narrow, dark spaces. For instance, cabbage white butterfly caterpillars often overwinter in fences, wall crevices, under tree bark, in soil cracks, or among weeds and crop debris near infested fields. Adult Lepidopterans possess wings, making contact-based control difficult; additionally, pests like the beet armyworm are nocturnal (active at night and hiding during the day). Some pests (like beetles) are adept at "playing dead" when threatened, making complete eradication very challenging.

3. Favorable temperatures

These pests thrive in warm conditions. In late spring and early summer, suitable temperatures trigger rapid reproduction and outbreaks. This period coincides with the crop's active growth phase, providing abundant nutrients to satisfy their voracious appetites.

4. Strong pesticide resistance

Their unique physiological structure reduces the absorption of insecticides, rendering standard treatments ineffective. Furthermore, if highly resistant individuals survive spraying, their immunity to the pesticide increases; subsequent generations will then exhibit even stronger resistance.

While a wide range of insecticides is currently available for controlling Lepidopteran pests, issues regarding their application—particularly against older larval stages—have led to significant resistance problems.

Agricultural control measures

During winter orchard or field cleanup, prune infested shoots and branches, and gather fallen leaves and debris for centralized burning or deep burial to reduce overwintering pest populations. During the growth periods of summer and autumn shoots, pay attention to bud rubbing and shoot control; promptly remove sporadically emerging tender shoots that appear too early or too late to ensure synchronized shoot flushing.
Strengthen fertilizer and water management. Before new shoots emerge, apply a root-strengthening agent (such as "Genlizhuang") combined with *Bacillus subtilis* to the root zone to promote uniform and vigorous shoot growth. Once the shoots have flushed, apply a foliar spray containing a leaf-strengthening agent (such as "Yelizhuang") and potassium dihydrogen phosphate to boost tree vigor, accelerate shoot maturation, and shorten the period of vulnerability to pests.

Regarding chemical control, using these agents alone is sufficient for Lepidoptera larvae up to the third instar, though rotating the agents is essential.

Emamectin benzoate

Non-systemic in crops but capable of penetrating epidermal tissue; highly active against Lepidoptera, mites, Coleoptera, Homoptera, and thrips; unlikely to induce pest resistance.

Acetamiprid

Acts via contact and stomach toxicity with strong systemic activity; inhibits acetylcholine receptor activity; effectively controls Hemiptera (aphids, leafhoppers, whiteflies, scale insects), Lepidoptera (leaf miners, small borers), and Coleoptera (longhorn beetles, thrips).

Chlorpyrifos

Acts via stomach toxicity, contact, and fumigation; effective against soil-dwelling pests and highly effective against Lepidoptera larvae.

Cypermethrin

Acts via contact and stomach toxicity with repellent properties; features strong knockdown power and rapid insecticidal action; highly effective against Lepidoptera pests and also effective against aphids and small green leafhoppers.

Lambda-cyhalothrin

Acts via contact and stomach toxicity; highly effective against various Lepidoptera larvae and possesses ovicidal (egg-killing) activity.

Bacillus thuringiensis

Highly effective against the larvae of Lepidoptera pests such as cabbage worms, diamondback moths, beet armyworms, and silver-Y moths. (7) Lufenuron

Lufenuron is highly effective against Lepidopteran pests on various crops; it demonstrates exceptional efficacy against resistant noctuid pests, such as the beet armyworm and the tobacco cutworm.

Chlorfenapyr

Chlorfenapyr has a broad insecticidal spectrum and a wide range of applications. It can be used on vegetables, fruit trees, and field crops to control various pests, including Lepidoptera and Homoptera, and is particularly effective against adult Lepidopteran pests.

Biological Control (Natural Enemies)

Release natural enemies—such as ichneumonid wasps and *Trichogramma* wasps—during the peak egg-laying period to control Lepidopteran larvae.

For Lepidopteran larvae beyond the third instar, applying a mixture of two insecticides yields better control results.

For tobacco cutworms beyond the third instar, a mixture of two insecticides is also recommended for superior efficacy. Suitable combinations include emamectin benzoate + chlorpyrifos; emamectin benzoate + chlorfenapyr; chlorpyrifos + indoxacarb; lambda-cyhalothrin + lufenuron; and high-efficiency lambda-cyhalothrin + chlorfenapyr, among others.

These pests exhibit "feigned death" behavior; promptly removing the dead insects from the ground after spraying enhances the overall control effect.

In addition, emamectin benzoate can also be used in mixtures for unexpected results in pest control. For specific formulations, please see: Don't use emamectin benzoate alone anymore! Try these excellent mixed formulations for highly effective pest control.