View Full Version : !!! A Blister Beetle In The Alfalfa!!!!

Dec. 28, 2009, 06:02 PM
I am :eek: for the first time ever, I have found a blister beetle in my alfalfa!

It's all going back tomorrow, of course...

how do I avoid this? I always feed a flake or two of alfalfa in the winter.. and this year it's the only thing the old horse can chew/ingest well...

crap :(

Dec. 28, 2009, 06:14 PM
Where did you get it?? Just want to make sure I don't buy any of it!

Dec. 28, 2009, 06:21 PM
How do you know it's a blister beetle? I have always wondered. I nearly have heart failure when I see a grasshopper carcass in the hay, I don't know what I'd do if I saw any kind of actual beetle. But for future reference, how does one tell if it's a dangerous beetle or just your garden-variety one?
And yeah, where are you? I only feed alfalfa, year round.

Dec. 28, 2009, 06:29 PM
I am northern NC and the hay came from Halls Hay. It is compressed alfalfa bales. Beautiful hay. The beetle fell out between two flakes. I tore the rest of it apart and did not find another one but still...

it is pretty obvious that is what it is, I think you would know if you saw one :( I bug-i.d'd it of course.

Dec. 28, 2009, 06:34 PM
Blister beetle pic; http://www.horsecareonline.net/ToxicPlants.htm
There seem to be several different kinds of all different colours and shapes, is that stripey one the only kind that hangs around in alfalfa ?

Guess not; http://www.ca.uky.edu/entomology/entfacts/ef102.asp

Tamara in TN
Dec. 28, 2009, 07:12 PM
Blister beetle pic; http://www.horsecareonline.net/ToxicPlants.htm
There seem to be several different kinds of all different colours and shapes, is that stripey one the only kind that hangs around in alfalfa ?

Guess not; http://www.ca.uky.edu/entomology/entfacts/ef102.asp

the striped one is the one you should worry the most about...I bet Tim Hall is gonna LOVE that;)

Tamara in TN

Dec. 28, 2009, 08:02 PM
That's always been my worst fear when feeding alfalfa. I'm so glad you saw it before feeding!

Dec. 28, 2009, 08:18 PM
To avoid blister beetle, try to buy hay baled before the blister beetles come out or after they are gone for the season. In my area, they come out after Memorial day, swarm around, feed, and lay their eggs by August, and they are usually gone after Labor Day. You will read a lot about beetle free areas, and about buying hay that hasn't been run over with a conditioner, but honestly, unless you buy 35# bales from the Amish, it will ALL have been crimped with a conditioner and I really don't believe people who say they don't have beetles. I think even So. Cal. has beetles now, which leaves No. Cal. and Canada as sources w/o beetles (maybe ND and Montana).

Beetles are only active in the summer months, when they come out to swarm. If you buy hay put up before or after beetle season, you have the best chance of protecting yourself. I have started buying hay that is baled AFTER the first frost to make WAY SURE the bugs are dead. Alfalfa is a cool season grass and can make it past a few light frosts. Last cutting, in October around here, is usually super fine stemmed and just fine for my horses. This year I made a deal with a grower to buy an entire cutting out of one field so that he would put it up in small squares. Otherwise he puts it up in huge squares for cattle. Sometimes first cutting is kind of stemmy and weedy, and the horses waste a little too much, but I will buy it if I'm looking at running out before September.

I would find a grower who can intelligently tell you when his beetle season is and work from there.

Meredith Clark
Dec. 28, 2009, 08:48 PM
Doesn't it take like 100 beetles to kill an adult horse? I always assumed that it would be fairly easy to see if you had an "infestation" before feeding it?

I feed alfalfa all year round and I've never seen one.

Tamara in TN
Dec. 28, 2009, 08:51 PM
Doesn't it take like 100 beetles to kill an adult horse? I always assumed that it would be fairly easy to see if you had an "infestation" before feeding it?

I feed alfalfa all year round and I've never seen one.

we have not either and we sell a bunch each year...but the grasshoppers were worse this year out west and WY even sent out a state warning about it over the summer

Tamara in TN

Dec. 28, 2009, 09:08 PM
Doesn't it take like 100 beetles to kill an adult horse? I always assumed that it would be fairly easy to see if you had an "infestation" before feeding it?

I feed alfalfa all year round and I've never seen one.What I remember learning years ago that the oils and 'juices' from just one beetle is enough to contaminate a whole bale and make a horse very, very ill or worse.

When I worked at the equine clinic there was a horse that came in with 'unrecognized' symptoms. We had just moved back from Florida where I was very acutely aware of the symptoms of Blister Beetle poisoning. I mentioned this to the vet but because we're in the northeast and don't have them here, he said that was very remotely possible. Well, turned out it *was* blister beetle poisoning. I'll never forget the smell of the DMSO the mare was getting ... it was nasty. Thankfully, she pulled through but it was pretty scary for awhile.

Dec. 28, 2009, 09:27 PM
What about cubes or alfalfa forage, like the triple crown alfalfa chopped forage? Should people worry about that as well? I'm just thinking, it would probably be next to impossible to know since it's all compressed and chopped...

Dec. 28, 2009, 09:48 PM
We don't have blister beetle here in the northeast. Happily, we do have a wonderful company that packages moist hay and distributes across the USA... LUCERNE FARMS http://lucernefarms.com/feeds_forage.shtml

I'm sure you can get the quantities you need from a distributor down in NC. Excellent product, highly recommended.

Dec. 28, 2009, 09:58 PM
I have started buying hay that is baled AFTER the first frost to make WAY SURE the bugs are dead.

Dead bugs do damage too.

"Cantharidin is the poisonous substance in blister beetles. It is comparable to cyanide and strychnine in toxicity. Although horses are considered to be very susceptible, comparable doses can poison cattle or sheep. Very small amounts of cantharidin can cause colic in horses. The substance is very stable and remains toxic in dead beetles. Animals may be poisoned by ingesting beetles in cured hay. There is no sampling method that can detect toxic levels of blister beetles."

Dec. 28, 2009, 10:52 PM
Unfortunately the Lucerne stuff isn't cheap. :dead:

I second cubes or pellets, soaked. Cubes will still give you the stem length, pellets won't... but I've known several horses that survived more than a decade on pellets & beep (no hay at all) and nary a colic...


Dec. 29, 2009, 01:47 PM
I always thought I was ok if buying alfalfa in Virginia? I don't feed it much but am thinking of finding some for my old guy who is about as picky as they come about hay.

Dec. 29, 2009, 02:31 PM
The heat from processing pellets neutralizes the toxin. And, yes, a small amount, one beetle, can sicken a horse.

I lived in Kansas for 20 years and we NEVER fed ANY local alfalfa hay because of blister beetles. In fact, my vet said he'd drop any customer that did.

I want to give my old girl the chopped alfalfa forage, is that processed enough to neutralize? Otherwise, I'll get her chopped timothy hay.

Dec. 30, 2009, 07:57 PM
I would burn it all. Then no horse is harmed. BB is BAD news. BAD. Horses can die from it.

Hopefully if the person you send it back to, doesn't "reissue" or "resale" it to somebody else.

good luck may a match or Scripto be with you.

Dec. 30, 2009, 08:09 PM
Thanks everyone.. I took it back. Got some nice timothy, will add alfalfa pellets..

scary little buggers, aren't they?!!!

Dec. 30, 2009, 08:23 PM
wow, what a wealth of information. i never knew this!

Dec. 30, 2009, 09:06 PM
one WING can kill an adult horse.
at least that is what I was always told. And they can be very hard to see.

Dec. 30, 2009, 10:37 PM
No blister beetles in Washington hay either...

Dec. 31, 2009, 10:11 AM
Useful FACTS from University of Kentucky can be found here;

More FACTS about Cantharidin Toxicosis from Purdue;

Horses are particularly susceptible to cantharidin, with the minimum lethal dose 1 mg/kg of the horse's body weight. Experimentally, as little toxin as 0.45 mg/kg of body weight has been fatal. One of the most important characteristics of this toxin is that it can exert its effects in the absence of the blister beetle bodies. Also, cantharidin withstands degradation by heating or drying, making it difficult to remove the toxin even during processing of alfalfa bales or alfalfa pellets where the beetles are commonly found.
Cantharidin is odorless and colorless, so it is important to monitor alfalfa hay for early detection of the blister beetles or their parts, as a preventive measure. If gone unnoticed within the alfalfa hay, once ingested it is highly irritating, causing acantholysis of the gastrointestinal tract, especially of the esophagus and nonglandular portion of the stomach, and of vesicles in skin or mucous membranes of horses. Cantharidin acts by altering mitochondrial metabolism via its inhibition of protein phosphatase, which is involved in the control of cell proliferation, activity of membrane-associated channels and receptors, and modulation of protein kinases and phosphatases. The inhibition of protein phosphatase 2A causes an increase in permeability of endothelial cells in a time- and concentration-dependent fashion by enhancing the phosphorylation of endothelial regulating proteins.
Clinical signs begin to appear 6-8 hours after ingestion of cantharidin. The affected horse may experience colic due to the irritation and vesicle formation in the gastrointestinal tract or because of decreased contractility, hypomotility and ileus. Also, it may be restless, irritable, sweating, have diarrhea and/or submerge its muzzle in water, (a common sign of cantharidin toxicosis). Cantharidin toxicosis also causes mucosal hemorrhage and inflammation of the urinary tract, which may manifest itself as signs of hematuria, stranguria and/or dysuria. The cardiovascular system is less frequently affected but, clinically, a horse may present with syndoronous diaphragmatic flutter (SDF). This is caused by alteration in membrane potential of the phrenic nerve and its discharge in response to electrical impulses generated during myocardial depolarization. The nervous system is less commonly affected, but an affected horse may present with aggressive behavior, seizure-like muscle activity secondary to colic, or muscle fasciculations. Most commonly, the horse presents with colic, depression, fever, dehydration, gastritis, esophagitis, and oral ulcers.
Laboratory findings can also be helpful in diagnosing cantharidin toxicosis. Serum calcium is usually markedly decreased and may remain low for prolonged periods. This hypocalcemia may be manifested clinically as SDF, tremors, or abnormal facial expressions, such as clamped jaws with lips drawn back. The serum magnesium concentration is also usually low, while creatinine kinase can increase markedly within the first 24 hours after ingestion. In acutely affected horses, urinalysis reveals markedly decreased specific gravity, often less than 1.101, and hematuria with or without myoglobinuria. Also, in acute cases, horses are frequently hyperglycemic and analysis of peritoneal fluid may reveal increased protein, greater than 4 g/dl, with normal numbers of white blood cells and fibrinogen levels. If the toxin has caused renal tubular necrosis and/or hypoproteinemia, there may be increases in serum urea nitrogen, approximately 50-70 mg/dl, and increases in creatinine, approximately 2-10 mg/dl. Total protein may be normal or increased during the first 24 hours, but then drops dramatically. Most commonly, the horse's laboratory findings include hypocalcemia, hypomagnesemia, and azotemia.
Cantharadin toxicosis can be confirmed using high pressure liquid chromatography (HPLC) to detect and quantify cantharidin in the urine of live or dead horses, and in the gastric contents, liver, or kidneys of dead horses. It is best to submit at least one pint of stomach contents or 20 ml of urine on ice for analysis.
At necropsy. erosions in the oral cavity, esophagus and stomach may be seen, as well as ulcerated to pseudomembranous enteritis. The most commonly reported gross pathologic lesions include necrosis and ulceration of the squamous lining of the distal esophagus, forestomach and urinary bladder.
Histologically, sheets of epithelium lifted from the serosal surface with normal epithelium in between can be seen, as well as hemorrhagic, ulcerative cystitis that appears as desquamation of epithelium, hyperemia, and marked hemorrhage in the bladder. Renal tubular necrosis is also visible. Occasionally, ventricular myocardial necrosis, which appears as foci or streaks in the papillary muscles and under the epicardium, may be seen both grossly and histologically.
There is no specific antidote for cantharidin toxicosis, so the treatment is usually directed at cantharadin removal, reduction, and immediate symptomatic therapy. The fatality rate can be as high as 65%, but with aggressive therapy, can be reduced to 20%. Horses with a toxic dose can die within 3-18 hours of onset, but, if they survive for 72 hours, recovery is more likely. Calcium and magnesium supplementation for prolonged periods of time is almost always indicated, but their administration should be carefully monitored and linked to serum chemistries. If the horse is exhibiting signs of gastritis, often indicated by submerging the muzzle in water repeatedly, sucralfate can be administered as a protectant. Non-steroidal anti-inflammatories (NSAIDs) can alleviate pain and protect against endotoxemia, but should be used with caution because NSAIDs are toxic to the kidney if the horse is dehydrated and if renal damage has occurred. The horse should also be stall rested for 5-10 days.
Prevention is the most effective way to avoid cantharidin toxicosis. The first cutting of hay is often free from blister beetles because the adults do not emerge until late May or June (in the southwest and southern plains, if cut before mid-May). Also, it is important not to crimp the hay during cutting so that the beetles can escape rather than get trapped and incorporated into the hay. Cutting the alfalfa at 10% or less can decrease the chance of poisoning because beetles are attracted to flowering plants. Scouting the fields for beetles and treating with a short residual insecticide before cutting helps to prevent blister beetle infestation. Sevin XLR has been has been used for prevention of infestation by blister beetles and other toxic insects. Carbaryl and parathion have also been commonly used to kill blister beetles, but have a pre-harvest waiting period that does not give them adequate residual activity to kill blister beetles that enter the field from spray time until just before harvest.
Blister beetle, or cantharidin, toxicosis is an important disease that should be considered when horses present with colic or acute death soon after ingestion of alfalfa. A definitive diagnosis may be determined if there is a history of feeding alfalfa or alfalfa-containing products, laboratory findings of hypocalcemia with or without hypomagnesemia, identification of blister beetles in hay or GI contents, and gross identification of ulcers in the distal esophagus, stomach and urinary bladder on necropsy. Confirmation using HPLC to determine the presence and amount of cantharidin in stomach contents or urine can be used. In order to prevent cantharidin toxicosis, proper cutting of alfalfa, surveying of fields and use of an insecticide, if necessary, are recommended.
-by Cindy Echevarria, Ross Student
-edited by Dr. Steve Hooser, ADDL Toxicologist

Aiello SE: 1998. Cantharidin Poisoning. The Merck Veterinary Manual 8th ed. Merck and Co., Inc. pp 2028-9.
Bahme AJ: 1968. Cantharides toxicosis in the equine. Southwestern Vet pp 147-148
Bauernfeind RJ, Higgins RA, Blodgett SL, Breeden LD: 1990. Blister Beetles in Alfalfa. Kansas State University Agricultural Experiment Station and Cooperative Extension Service. June.
Carlton WW, McGavin MD: 1995. Thomson's Special Veterinary Pathology. 2nd ed., Mosby. pp 27-28, 243-244
Helman RG, Edwards WC: 1997. Clinical features of blister beetle poisoning in equids: 70 cases (1983-1996). JAVMA 211: 1018-21.
Graziano MJ, Pessah IN, Matsuzawa M, Casida JE: 1998. Partial characterization of specific cantharidin binding sites in mouse tissues. Am Society for Pharmacology and Experimental Therapeutics. 33: 706-712.
Guglick R et al: 1996. Equine Cantharadiasis. Compendium Cont Ed Pract Vet. 18:77-83
Knapp J, Boknik P, Luss I et al: 1999. The protein phosphatase inhibitor cantharadin alters vascular endothelial cell permeability. Pharmacol 289: 480-486
Ray AC, Kyle AL, Murphy MJ, Reagor JC: 1989. Etiologic agents, incidence, and improved diagnostic methods of cantharidin toxicosis in horses. Am J Vet Res 50: 187-191.
Ray AC, Tamulinas SH, Reagor JC: 1979. High pressure liquid chromatographic determination of cantharidin, using derivatization method in specimens from animals acutely poisoned by ingestion of blister beetles, Epicauta lemniscata. Am J Vet Res 40: 498-504.
Walter WG, Cole JF: 1967. Isolation of cantharidin from Epicauta pestifera. J Pharm Sci 56: 174-176.

Dec. 31, 2009, 10:26 AM
IMO, better to err on the safe side. For this reason, I never feed alfalfa - regardless of how beautiful it sometimes looks @ my local feed store. Sad, b/c the horses love it. I leased one of my youngsters to an eventer in Idaho and sent a bale of his (high quality coastal) hay with him to make the transition. They tried to 'wean him' off of his hay and onto their alfalfa. After the first feeding, he'd only use the coastal as a pillow. :))

Dec. 31, 2009, 10:44 AM
I would burn it too. The bb infested hay is not worth the risk. It damages the horse's kidneys and kidney damage is only detectable in blood tests when they (kidneys) are 70 % damaged minimum. I am in Florida and only buy hay from up north as a result. You should post this in the hay forum too. This situation reflects the value of a hay vendor like Tamara who loves horses and understands their needs. I am scared to buy hay from a cow hay vendor.

A bit of trivia: aren't blister beetles traditionally the source of red dye for SW Native American textiles? Someone back in ancient times found perhaps an efficient way to dispose of blister beetles there. Maybe in ancient times they learned they were toxic to horses and so they tried to pick them all out ( I know this is not really possible in reality) and make red dye from them.

Dec. 31, 2009, 10:50 AM
I suppose that this is a reason to feel better about the fact that the ground is frozen solid today.

Most bugs don't survive the freeze, therefore we feed beautiful alfalfa.

It certainly makes the feed mixing simple because there is very little needed to make your ration perfect. Just add exercise.

We travel a lot with our horses and we try to take our own hay. One trip we were a long long way from home and had to feed the local hay. It looked terrible, and it was some kind of grass. I was concerned that our picky eater wouldn't touch the stuff. He surprised us by scarfing up every scrap. So again, looks can be deceiving.

Dec. 31, 2009, 11:09 AM
so does anyone know how safe alfalfa in VA is? How about alfalfa cubes and pellets- seems the article posted above says heat does not affect cantharidin- but how do we know the manufacturers are careful about blister beetles???

Dec. 31, 2009, 11:12 AM
A bit of trivia: aren't blister beetles traditionally the source of red dye for SW Native American textiles? Someone back in ancient times found perhaps an efficient way to dispose of blister beetles there. Maybe in ancient times they learned they were toxic to horses and so they tried to pick them all out ( I know this is not really possible in reality) and make red dye from them.

Cochineal beetles(Dactylopius confusus) are the source of red dye.

Dec. 31, 2009, 11:20 AM
Thanks Equibrit i was wondering about that. Hope it is not too cold where you are. Happy New Year!

Katy Watts
Dec. 31, 2009, 11:42 AM

We need to be most careful of blister beetles when grasshoppers are bad. BB's eat grasshopper eggs. Cuttings later in the season will be higher risk. As a crop consultant in CO, I mostly see the black beetles, although we can get the gray striped ones, too. They differ in their toxicity. The grasshoppers have been very thick the last 2 years due to higher than normal spring and summer moisture.

The reason we are seeing more BB is because nearly everyone conditions or crimps alfalfa to get it to dry faster. If one windrows without conditioning, and turns at least once (the old fashioned way) the beetles do not get crushed and scurry away. So perhaps finding alfalfa grown by a small time, old fashioned farmer with ancient equipment is lower risk?

Jan. 3, 2010, 08:02 PM
I saw a bunch of beetles one day in the hay stall and flipped out. Looked exactly like blister beetles, but on very close examination of the corpse and comparison with internet pictures, was not blister beetle. Was a very very similar looking beetle but was completely harmless. They tend to live in dark dank corners of barns.
Took off a year from my life though.

Jan. 3, 2010, 08:14 PM
Ackk!! Thanks for the information-- I'm in SC and have ordered the compressed alfalfa from Halls Hay for years...I'll be shaking all my bales to pieces digging in them, thats for SURE!

Jan. 3, 2010, 09:56 PM
Last semester I had a killer Equine Nutrition class in which we discussed this in-depth. From my notes: (some of which summarizes what was said previously)

- Takes 2-3 beetles to kill a horse but 1 will cause significant pain
- BB's like feeding on aphids which like feeding on the BLOOMS of the Alfalfa (important!)
- Cantharatin travels through the bloodstream to the kidneys and causes blisters inside the digestive tract
- Affects mostly southern US, Texas

How to avoid
- Cut it before it blooms
---- If there are no blooms, there are no aphids. If there are no aphids, there are no blister beetles.
- Don't put it through a conditioner
---- Once the alfalfa is cut and laying on the ground, the beetles will just scurry out of the alfalfa and run for cover unless you use a conditioner before they've had a chance to scurry. A dead, squished beetle can't scurry very far...
- Check hay in field, BB's will be mainly on edges of hayfield near brush

If I knew my hay came from an area that had them, I wouldn't feed it unless I saw the hay in the field and knew it was cut before it bloomed, and I'd get that in writing (But I'm paranoid.)