What is a Warble?

The warble is a hairy fly that becomes parasitic on cattle, deer and horses. It is scientifically known as the genus Hypoderma. Hypoderma lineatum is the term for horse warbles, and Hypoderma bovis is the term for cattle warbles. The warble is also known as a “heel-fly,” “bomb fly” and “gad fly” in common language. The larvae are often referred to as “cattle grubs” or “wolves.”

Typically the warble lays its eggs on the cattle’s leg hairs. One fly may lay up to eight hundred eggs on one cow. When the eggs hatch, the larvae crawl down the hair, and onto the skin, penetrating it to get onto the subcutaneous level — the level just below the skin. This is incredibly irritating to the animal.

After months of traveling through the cattle’s body, and growing larger, the larvae typically settle on the cattle’s back, near the spine, and swell. The swelling results in a pimpled cyst under the cattle’s skin. There, the larvae molt for thirty days. Then, a mature larva squirms out of the cyst and falls to the ground to endure a 35 to 60 day cocoon-like pupation stage. After this stage, the adult warble will emerge to begin the cycle again.

Though the warbles do not cause direct harm to the animal, they can pose many harmful effects. Since the fly is so persistent, and the hatched larvae cause so much discomfort to the animal, the animal may not feed properly due to the constant strain. This can result in the animal may lose significant weight, resulting in decreased milk production. Value of the carcass hide can also depreciate when riddled with holes from larvae emerging from cysts.

While warble refers to this type of pesky fly, it also refers to a musical trill or a delightful succession of low notes. The musical definition is derived from the 14th century Old High German word for whirlwind. In this use, the word can also be used as a verb, as in, the act of warbling. Warbling is to sing with many twists and turns; that is, with a variety of pitches that change quickly.

A warble is a skin lump or swelling caused by the larval stage of certain species of flies, commonly the botfly. These larvae burrow under the skin of mammals, creating a noticeable bump. As they mature, they cause a condition known as myiasis, where the animal host's tissue is invaded by the developing larvae.

Animals typically get warbles through direct contact with botfly eggs. The eggs can be deposited on the animal's skin by the adult fly or transferred when an animal brushes against a surface where eggs are present. The warmth of the host's body prompts the eggs to hatch, and the larvae then penetrate the skin.

Warbles can be harmful to animals as they can cause discomfort, irritation, and secondary infections. In severe cases, according to veterinary experts, the presence of multiple larvae can lead to systemic health issues. However, most healthy animals can tolerate a few warbles without serious health consequences.

Yes, humans can get warbles, although it is less common. Human cases usually occur when individuals are exposed to botfly habitats or travel to areas where these flies are endemic. The larvae can penetrate human skin just as they do with animals, leading to similar symptoms and requiring medical treatment.

Treatment for warbles in animals involves the careful removal of the larvae from the skin. Veterinarians may perform this procedure under local anesthesia to minimize discomfort. After removal, the wound is cleaned and sometimes treated with antibiotics to prevent infection. It's important not to squeeze the larvae out, as this can cause inflammation or an allergic reaction.

Preventing warbles involves controlling the botfly population and protecting animals from exposure. This can include using insect repellents, keeping animals indoors during peak botfly activity, and maintaining clean living environments. Regular veterinary check-ups can also help detect and treat any infestations early, minimizing the risk of complications.