Friday, July 9, 2010

Pest of the Week: Wireworm


Wireworm, larvae of the Click Beetles (Many species)

Wireworms are pests on many crops like potato, corn, grain crops, and other various vegetables. They live for years in the pupal stage, therefore making them a difficult pest to eradicate.

Life Cycle: Wireworm adults (click beetles) lay eggs in groups in the soil. Adults are active at night during the summer months. Eggs hatch and larval forms dwell in the soil for 2-5 years until pupating into the adult click beetle. The inch-long larvae are light brown in color. They seek deeper soil when the weather is very hot or very cold but are commonly found in the top 8-10” of the soil. Larvae tend to be found in wetter parts of a field or in fields that were recently turned from sod into cropland; although, larvae can be found in fields that have been in cropland for many seasons.

Click Beetle

Plants affected: Crop damage occurs during the wireworm’s larval stages. Larvae feed on seeds, roots, and tubers. Wireworms are attracted to and feed on corn and grain seed, and potato seed pieces and tubers. This feeding can reduce a crop stand, thereby reducing overall yields. Wireworms will also burrow into tubers damaging the crop and making it unmarketable. When soil is drier, wireworm damage tends to be higher on tuber crops due to the pest seeking moisture from the crop.

Control: Population density estimates can be inferred from larvae caught in bait stations. Bait stations consist of a shallow hole dug in the field, 6-8” deep and 3-4” wide, filled with corn or wheat, and covered with a piece of black plastic. The bait hole is left for a week then dug up to count wireworm larvae. Several of these bait holes should be placed in a one-acre field to assess accurate populations. Screening can also give a grower an estimate of how much wireworm pressure is in a field. Screen a one foot square area, 6-8” deep. Several of these samples should be taken in a one-acre field. If there is one wireworm found in the square foot of soil screened, then the pressure is considered high. This is not an adequate method for control. Rather, it is a way to determine if a field is appropriate for crops that are susceptible to wireworm damage. If wireworm pressure is deemed high, choose crops that will not be as susceptible to their damage. There are conventional pesticides that are labeled for wireworm. A biological control consisting of a fungus that infests insects has been scientifically researched and proven as effective as conventional controls for wireworm. Johnny’s is investigating carrying such a product. Read all product labels in full and follow label instructions as specified for that particular product.



Anonymous said...

Thanks for this. Look fwd. to Johnny's carrying the product that safely eliminates wireworms. Last year they destroyed my crop of cutting snapdragons. I didn't even plant any this year.

Unknown said...

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