It is unfortunate but the blister beetle has plagued the alfalfa industry
Know where your hay comes from
Buy from Hay USA Inc.
The people you can trust.
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Blister beetles are one-half to one inch. long and have soft bodies. The
head is broad and vertical. The section of the body between the head
and the wings (prothorax) is narrower than the wings, and narrower than
the head. It appears that the insect has a neck. The wings are soft and
flexible, and the legs are long. Striped blister beetles are about 5/8
inch long and one-fourth as wide. They are gray to brown with yellow
stripes running lengthwise of the wing covers. The ash-gray blister beetle
is about 1/2 inch long and is completely gray. The black blister is about
1/2 inch long and is solid black.
The larvae of the blister beetles destroys grasshopper egg pods. Infestations
often occur during or just following a grasshopper outbreak. The black
blister beetle adults are largely pollen feeders, but they also feed
on alfalfa blossoms. Blister beetles have an oily substance, cantharidin,
in their body fluid that causes large blisters to form when a beetle
Blister beetles have a wide host range including alfalfa, clover, soybean,
potato, tomato, melon, cotton, and eggplant.
Cantharidin was first isolated in 1810. It is odorless and colorless.
- It is secreted by the male blister beetle and
given to the female during mating. Afterwards the female beetle will
cover its eggs with it as a defense against predators.
- Horses are highly sensitive to cantharidin and
it is often deadly.
- For horses a lethal dose is approximately 1
mg/kg of the horse's body weight.
- Horses may be accidentally poisoned when fed
bales of Alfalfa with blister beetles in them.
- Cantharidin is comparative to cyanide and strychnine
- Cantharidin will remain toxic in dead beetles.
- There is no sampling method that will detect
Cantharidin in cured baled hay or cubed or pelleted hay.
- Cantharidin can not be broken down by heat or
Cantharidin can cause sever inflammation and the formation of blisters
on the skin. If absorbed through the intestines, symptoms can include
inflammation, blisters in the mouth, straining, temperature, increased
heart rate and respiration, sweating, diarrhea and frequent urination
within the first 24 hours.
This is accompanied by secondary infection and bleeding. Calcium levels
in the horses may be drastically lowered and heart muscle tissues destroyed.
Animals can die within 24 to 72 hours, so it is imperative to contact
a veterinarian as soon as a blister beetle poisoning is suspected.
Toxic to Livestock:
Cantharidin is toxic to livestock. Cantharidin is contained in the (blood)
of the beetles and may contaminate forage directly when beetles are killed
during harvest. Handling these insects may result in blisters, similar
to a burn. Blister beetles have been a serious problem in alfalfa in
the northern United States, the Midwest, and the south for many years.
We have found West coast Alfalfa to be safest. We always recommend checking
your alfalfa for extra security. Nothing is 100%. Your horse depends
There is beautiful hay through out this country and Canada and very reputable
producers who take every precaution in regards the beetle epidemic.
Beware of mechanical conditioners. Mechanical conditioning crimps the
hay to create a soft green texture by removing moisture within a matter
of hours. Unfortunately this kills the Blister Beetles trapping them
in the hay. A dead beetle is deadlier than a live beetle! Please don’t
be taken by pretty hay, go for safe hay. Beware of a salesman that says
that there are no Blister Beetles in their state. Blister Beetles are
in every state in the United States. Educate yourself, check your hay before feeding. Your horse
depends on you!
Don't be scared to feed alfalfa, learn about Blister
Beetles. Hay USA has Safe hay!