What are the tiny flying insects that swarm around horse manure?

The tiny flying insects that swarm around horse manure are most likely stable flies, also known as horse flies or biting flies.

Here's why:

* Attraction to Manure: Stable flies are attracted to the odor and warmth of decaying organic matter, especially manure.

* Appearance: They are small, grey, and have a distinctive piercing-sucking mouthpart.

* Life Cycle: Stable flies lay their eggs in decaying vegetable matter, including manure. The larvae develop in this environment, emerging as adult flies to feed on the blood of horses and other animals.

Other Possibilities:

While stable flies are the most common culprit, other insects might be present:

* House Flies: These flies are attracted to various organic matter, including manure, but they are larger than stable flies and less likely to swarm.

* Dung Beetles: These beetles are attracted to manure but are not flying insects.

If you're experiencing a swarm of tiny flying insects around manure, it's important to identify the specific type to determine the best control methods.