What are the control methods for the white-spotted flower chafer?

The white-spotted flower chafer sporadically mainly damages corn, grapes, tomatoes and apples.

I. Morphological characteristics and living habits of the white-spotted flower chafer

The adult is 17-24 mm long and 9-12 mm wide, oval-shaped, with a bronze luster, and its body surface is scattered with numerous irregular white downy spots. Only 1 generation occurs each year. It overwinters as larvae in soil or in compost made from rotted straw. It starts activity in March of the following year. In late April and early to mid-May it damages corn seeds and seedlings, adults appear in May, and June-August is the peak occurrence period. Adults are active during the day, have a feigning-death habit, are attracted to the smell of alcohol and vinegar, are very strong fliers, and often gather in groups to damage the male flowers, pistil styles and young kernels during the grain-filling stage of corn, and lay eggs in the soil. The larvae (white grubs) mostly feed on soil or on decaying matter in rotted and composted material.

II. Causes of occurrence

According to analysis, the causes of this insect's occurrence are: some residual sheep manure remained in some abandoned sheep pens in this breeding park, and this insect parasitized in the sheep manure. Because the weather was dry with little rain, after emerging as adults they drilled out of the soil and flew onto the fruits of plants such as corn, grapes and tomatoes to cause damage.

III. Control measures

(I) Based on the characteristic that adults gather in groups to cause damage, manual capture can be adopted in the morning and evening or on cloudy days when the temperature is low, and the captured insects can be killed together. Alternatively, the manually captured adults can be mashed, soaked in water for 2-3 days, the liquid filtered out, diluted with water and sprayed onto the fruits, which can repel adults and prevent them from damaging the fruits. Poison bait made from sawdust + trichlorfon emulsifiable concentrate + sugar + vinegar can also be used for trapping and killing.

(II) Promptly clean up the residual sheep manure in the sheep pens, or pile the sheep manure centrally for composting, and through high-temperature fermentation and decomposition reduce the places where adults lay eggs and reproduce.

(III) Make use of the adults' feigning-death habit, and during the peak period of adult occurrence, shake them down and kill them when the temperature is low in the early morning.

(IV) For fields where insect damage occurred this year, plow the land in late autumn or early winter to reduce the insect population and lessen the damage in the second year.

(V) Chemical control: spray or drench with 50% phoxim emulsifiable concentrate at 1000 times dilution, 2.5% deltamethrin emulsifiable concentrate at 2000 times dilution, and 2.5% cyhalothrin emulsifiable concentrate at 2000 times dilution.