Why are horse flies called horseflies?

Horseflies are called horseflies because they are notorious for their painful bites, which they often inflict on horses.

Here's why:

* Their diet: Horseflies are blood-feeding insects. They primarily target large animals like horses, cattle, and humans.

* Their bite: Their bite is painful because they don't just pierce the skin and suck blood. They also inject saliva containing an anticoagulant, which prevents the blood from clotting. This causes itching, swelling, and sometimes allergic reactions.

* Their attraction to horses: Horses are particularly susceptible to horsefly bites because they are often large and stationary, making them easy targets.

So, the name "horsefly" reflects their common target and the painful experience they inflict on these animals.