Detailed Explanation of the Harm Caused by the Meadow Moth and Its Control and Pesticide Methods

The meadow moth (Loxostege sticticalis), of the family Crambidae, also known as the yellow-green striped moth, beet webworm, and the net-cone-fronted aphid moth, is a highly polyphagous major pest, mainly damaging sugar beet, soybean, sunflower, potato, hemp, vegetables, medicinal herbs and many other crops. So what harm does the meadow moth cause? What pesticide is used to control it?

In early to mid-June, the overwintering-generation adults of the meadow moth suddenly increased in eastern Inner Mongolia, southwestern Heilongjiang and western Jilin, with high numbers of insects under lights and in the fields, and the adult occurrence area exceeded 15 million mu. Recently, the number of overwintering-generation adults in Northeast China has gradually decreased, while the number of first-generation larvae has clearly risen, with high larval numbers and severe damage in some fields that are suitable for egg-laying and have abundant weeds. According to preliminary statistics, as of June 20, the national first-generation larval occurrence area of the meadow moth exceeded 7 million mu.

The Harm Caused by the Meadow Moth

The meadow moth overwinters as mature larvae in silken soil cocoons. In the following spring, as daylight increases and temperatures rise, the overwintering larvae begin to pupate, generally entering the peak emergence period from late May to early June. After the overwintering-generation adults emerge, they migrate from the overwintering sites to the occurrence sites, breed for 1 to 2 generations there, then migrate back to the overwintering sites, where they lay eggs and reproduce until the mature larvae burrow into the soil to overwinter. Newly hatched larvae feed on the leaf mesophyll, leaving the epidermis; after growing larger, they can eat the leaves into notches or leave only the veins, making the leaves appear net-like. When outbreaks occur, they also damage flowers and young pods.

How to Control the Meadow Moth

1. Agricultural control

Because the meadow moth prefers to lay eggs on weeds such as lamb's quarters and saltwort, attention should be paid to eliminating weeds on wasteland, around ponds, and at field edges and field ends to reduce the number of eggs laid by the meadow moth, and field weeds should be removed promptly, which can eliminate some of the insect sources. Autumn plowing or winter plowing can also eliminate some of the cocoons overwintering in the soil, which can both lower control costs and improve control effectiveness.

2. Chemical control

Because the meadow moth has the characteristics of clustered migration and gluttonous feeding, the control period is relatively concentrated, and control should be carried out promptly before the larvae reach the 3rd instar, that is, within 10-12 days after the peak hatching period. Due to uneven distribution and hidden damage, it is important to emphasize timely field inspection and carry out “spot treatment.” When larval density in the field is high and damage is scattered, farmers should be organized for joint control and large-scale unified prevention and management.

Pesticide selection: The meadow moth has no pesticide resistance, so general insecticides can be used. Considering all factors, it is advisable to choose pesticides that are low in toxicity, fast-acting, safe for crops and relatively economical.

Recommended pesticides:

① On sunny afternoons during the peak activity period of adult meadow moths, spray pyrethroid insecticides to kill the adults (the dosage must not be increased when used on corn and sorghum, otherwise phytotoxicity will occur).

② Larval control: At the young larval stage (1st-2nd instar), use chemical pesticides for control: 2.5% Kung Fu emulsifiable concentrate 12-20 milliliters, diluted with 50 kilograms of water per mu for spraying. 4.5% beta-cypermethrin 30 milliliters per mu.

③ Use a tractor-mounted suspension sprayer, with the tractor kept in second gear, and a spray volume of 30 kilograms per mu for control, or use knapsack motorized sprayers, with each person spaced 5 meters apart, spraying in a single line.

3. Physical control

Set up blacklight lamps in soybean fields to trap and kill adults.