Alfalfa hay-Blister beetle

Epicauta spp.

Pest description and crop damage Large, gray to black elongate beetles feed on foliage in late spring and summer. Feeding on hay causes little, if any, crop injury. However, blister beetles are a serious concern for hay producers and livestock owners because the cantharidin in the blister beetle causes cantharidiasis or blister-beetle poisoning when livestock eat hay that contains it. Cantharidin irritates animals' gastrointestinal and urinary tracts, may irritate the mucous lining of the mouth, may affect behavior, and sometimes kills horses, cattle, and sheep. Symptoms include blisters on the tongue and mouth, colic, diarrhea, blood or intestinal lining discharge in stools, and problems with urination or bloody discharge in urine. If you suspect blister-beetle poisoning, contact a veterinarian immediately. For additional information, see: Blister beetles; Pests or Beneficial Predators? http://cru.cahe.wsu.edu/CEPublications/FS113E/FS113E.pdf.

Management-chemical control

  • carbaryl (numerous products) at 0.5 to 1 lb ai/a. PHI 7 days for grazing or cutting. REI 12 hr. Do not apply more than once per cutting. Carbaryl may burn or yellow hay under some conditions (wet foliage, high humidity). Carbaryl is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply carbaryl or allow it to drift to blooming crops if bees are visiting the treatment area. Latex-based formulations, such as Sevin XLR Plus, are less hazardous to bees. (Group 1A)
  • chlorantraniliprole/lambda-cyhalothrin (Besiege) at 0.059 to 0.088 lb ai/a. PHI 1 day for forage and 7 days for hay. REI 24 hr. Minimum of 5 days between applications. Do not exceed 0.12 lb ai of products containing lambda-cyhalothrin or 0.2 lb ai of chlorantraniliprole-containing foliar products per acre per growing season. Refer to product labels for application limits if products containing gamma-cyhalothrin and products containing lambda-cyhalothrin are to be used in the same season. This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops if bees are visiting the treatment area. (Groups 28 and 3A)
  • chlorpyrifos/gamma cyhalothrin (Cobalt) at 0.38 to 0.76 lb ai/a. PHI 14 days at low rate to 21 days above 0.52 lb ai/a. REI 1 day. Do not apply Cobalt or any other product containing chlorpyrifos more than once per cutting, or more than 4 times per season. Refer to product labels for application limits if products containing gamma-cyhalothrin and products containing lambda-cyhalothrin are to be used in the same season. This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops if bees are visiting the treatment area. (Groups 1B and 3A)
  • gamma-cyhalothrin (Declare) at 0.01 to 0.015 lb ai/a. PHI 1 day for forage harvest or 7 days for hay harvest. REI 24 hr. Do not exceed 0.015 lb ai/a per cutting or 0.06 lb ai/a per season. Refer to product labels for application limits if products containing gamma-cyhalothrin and products containing lambda-cyhalothrin are to be used in the same season. This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops if bees are visiting the treatment area. (Group 3A)
  • lambda-cyhalothrin (Warrior II) at 0.02 to 0.03 lb ai/a. PHI 1 day for forage harvest or 7 days for hay harvest. REI 24 hr. Apply only to pure stands. Do not apply when bees are actively foraging. Do not exceed 0.03 lb ai/a per cutting or 0.12 lb ai/a per season. Refer to product labels for application limits if products containing gamma-cyhalothrin and products containing lambda-cyhalothrin are to be used in the same season. This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops if bees are visiting the treatment area. (Group 3A)