Feline's and Bot Flies: what to know

In recent weeks, HATS has received cats with bot flies- large, fuzzy flies that kind of look like bees. These bot flies are found when lumps are felt under the skin of cats and identified as bot flies by a small hole in the lump.

The typical host of bot flies is small mammals like rabbits or squirrels. The flies lay their eggs near the entrances to their dens and soon the larvae attach to their fur. The larvae make their way to a hole in the host's body and migrate through their body to the tissue under the skin where they make their breathing hole and “warble.”

Inside the host, the bot fly will continue to mature and then make its way out of the hole and fall to the ground, where it will become an adult fly.

When a bot fly chooses a cat as its host, it has most likely been confused. Cats often hang around the dens are smaller animals and can become the victim of bot fly larvae waiting for some fur to pass by. The lifecycle of the bot fly seems to be the same regardless of their host, however, loss in the ability to reproduce can occur for bot flies that make this mistake.

Any age or gender of cat can get bot flies and it is not uncommon, especially in the northeastern United States. Mostly an issue in the late summer and early fall, cats can begin showing the lumps or warbles under the skin. The small breathing hole is what indicates bot fly clearly. The cat may lick or scratch at the warble which could cause more irritation or fur loss.

After noticing a bot fly warble on your cat, talk with your vet about removal options for the larvae. Vets typically can remove the larvae by: anesthetize the cat and remove surgically by widening the opening and removing with tweezers, if the cat is calm they can sedate the larvae and easily pull it out, or pour a liquid/salve that eliminates their breathing into the hole and waiting for it to rise up and be easily removed.

Making sure the entire larvae is removed and it hasn't been harmed much in the process. If the larvae have been crushed or pieces have been left behind it can lead to chronic infections or potential fatal anaphylaxis.

Stopping your cat from going outside is the best way to prevent bot flies, if that isn’t possible a monthly preventative can be used but definitive research hasn’t been done yet.