Wire Worms Wire worm The larvae are hard, slender, wire-like worms yellow to a dark brown copper color. They are ½ to 2 inches in length when mature. It is suggested that wire worm damage has become more common with the advent of reduced tillage. The adults are attracted to grassy areas for egg laying such as a grain crop. Last year’s wheat stubble could be an indicator of wireworm populations. Wire worms in soil in hand Life Cycle: The larvae overwinter in the soil and become active when soil temperatures reach 55 degrees. Adult females emerge, mate and burrow back into the soil to lay eggs. They can reemerge and go to other sites in the field to lay eggs. The egg laying soil preference can vary from light well drained soils to low spots where moisture levels are higher and clay is present. This often results in ‘hot spot’ infestations in the field. Damage: The wireworms feed on the developing roots of a seedling or a germinating seed. The seedling often dies before emergence or wilts shortly after emergence. Heavy damage can occur in spots in the field requiring replanting of that area. Economic Thresholds: See the scouting method below. Scouting Method: Soil sampling (digging for the wireworm) is required to determine if wire worm is present. NDSU suggests when digging soil samples, 12 or more wireworms in 50 ‘3-inch by 3-inch’ samples, is likely to result in damage. Management: There are excellent insecticide seed treatments available that will eliminate wire worm damage. Most seed companies now sell only treated seed with Cruiser® or Idol® primarily for wireworm control. Research: This is not a research priority since excellent seed treatments are available. Photos: Visit the Photo Gallery. Source: NDSU Extension Bulletin 25 Sunflower Production Handbook, NDSU Extension Service, September 2007 and High Plains Production Handbook June 2005 For further information, click on the links below. Another resource about Insects can be found in the Archive section of The Sunflower magazine. Additional Documents High Plains Sunflower Production Handbook (1554 kb .pdf file) Download Adobe Acrobat Reader NDSU Extension Bulletin 25 - Revised 9/2007 (5592 kb .pdf file) Download Adobe Acrobat Reader
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