what to use when you are infested with striped blister beetles

Blister beetles in alfalfa hay

Jared Goplen, Extension educator; Krishona Martinson, Extension equine specialist; Bruce Potter, Extension IPM specialist

At that place accept been an increasing number of blister beetle sightings in Minnesota alfalfa fields this year. Blister beetles are rarely problematic in Minnesota, but the drought atmospheric condition have caused some business concern for blister protrude-infested alfalfa. If consumed in hay or haylage, blister beetles tin crusade health bug and death in horses, cattle, sheep, and other livestock.

Key points

• Blister beetles have been found in many areas of Minnesota this year
• Blister beetles contain cantharidin, a toxin that causes health bug and death in livestock when consumed in large enough quantities.
• Horses are more sensitive to cantharidin than cattle, sheep, or other classes of livestock.
• To foreclose problems, sentry fields 1-1.v weeks prior to harvest, avoid harvesting alfalfa beyond 10% flower, and watch for protrude "swarms" during harvest.

What are blister beetles?

Blister beetles are attracted to and feed on the flowers, pollen, and leaves of blooming alfalfa and weeds. Developed blister beetles are long, narrow beetles (0.five to one.25 inches long) with a wide caput and antennae that are straight and most ane third their total torso length.

Several species exist, including black, ash gray or striped beetles, each having unique colour patterns (Figures 1 & 2). Striped and ash gray blister beetles seem to be the most common this year.

Blister beetles tend to be more numerous in alfalfa that was produced in arid southern states and plains states where grasshoppers are problematic, because developing beetles feed on grasshopper eggs. Every bit a upshot, blister protrude populations are typically greatest in areas where grasshoppers were present the prior year.

Cicatrice beetles produce a defensive compound chosen cantharidin. Striped blister beetles contain more of this compound than black or ash gray blister beetles. The level of cantharidin produced is highly variable and released when the beetle is crushed during hay making. Cantharidin remains toxic in expressionless beetles and does not decrease during storage.

Horses are more sensitive to cantharidin than other types of livestock, though they express similar symptoms when bully enough quantities of cantharidin are consumed. When eaten, specific symptoms in horses include the following:

• sores or blisters on the natural language and in the mouth
• colic
• straining
• increased temperature
• depression
• increased middle and respiratory rates
• aridity,
• sweating
• diarrhea, bloody feces, and frequent urination.

If you lot doubtable cantharidin poisoning, contact your veterinary immediately. In that location is no specific antidote beyond supportive care, which includes mineral oil, intravenous fluid therapy, activated charcoal, and analgesics.

Minimize adventure at harvest

Although the risk of harvesting blister beetles in hay cannot exist eliminated, it can be minimized past scouting alfalfa fields prior to harvest and by cut hay earlier full bloom. In the Midwest, protrude populations are relatively low until mid-summer (e.thou. July and August), so first and second cutting tend to accept minimal infestations. Beetles are more probable to be found in flowering alfalfa hay where grasshoppers were present the prior year, which was the case for areas of Minnesota last twelvemonth.

Hay that is simultaneously cut and crimped with a mower conditioner is more than likely to kill beetles, keeping them in the windrow. Notwithstanding, crimping speeds drying, which is important for harvesting quality hay. Live beetles will typically leave the windrow prior to harvest.

Cutting alfalfa at less than ten% bloom reduces the number of beetles. Farmers should watch for beetle "swarms" during harvest and end to allow the beetles to disperse. Chemical command is possible if beetles are present but may not be the best option because expressionless beetles containing cantharidin may still end upwardly in hay.

What can hay buyers practice?

When buying hay, buyers should acquire as much equally possible almost its production, including who produced it, where it was produced, and the cut appointment and maturity at harvest. If details aren't available, owners should pay close attending to alfalfa hay that was mature or flowering when harvested. It is nearly impossible to detect blister beetles while feeding contaminated hay. This is because the beetles tend to swarm, pregnant only a few bales, or even just parts of bales from an entire field may be infested.

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Source: https://blog-crop-news.extension.umn.edu/2021/08/blister-beetles-in-alfalfa-hay.html