It's an Ill Wind ...

As I was sitting in the back yard, peacefully contemplating the beauty of the afternoon, all of a sudden I heard the sound of thundering hoofs. Getting up to find out what was going on, I discovered Rose galloping about the top field. At first I thought she was playing, as I saw her bucking at Chloe. Closer investigation, however, revealed that she was somewhat distraught. She ran to the gate when she saw me, as if to say - "Get me out of here!" And she refused the grass I picked to offer her.

One of Rose's less endearing characteristics is that she tends to blame the person standing closest for whatever is disturbing her. Hence the bucks at Chloe, and when she had gas colic, she would pin her ears at me when she felt a twinge. So I went in to the field and tried to figure out what was up from a distance. I thought for sure it had to be the mother of all horse flies, or a giant tick.

It didn't take long to see what the culprit was: a hovering bot fly, trying to land on Rose, which she just couldn't shake no matter how fast she galloped.

It's interesting that horses dislike bot flies so much. It can't hurt when they deposit their eggs. Yet those eggs have the potential to be damaging to the horse, and it seems horses have been given the ability to recognize the danger.

Rose calmed down eventually. Maybe the bot fly had its way and left. Or maybe she finally managed to kick it to pieces.

But there may be another side to the bot fly. For a couple of years, George had a round bald scar, about an inch and a half in diameter, on his shoulder - put there by an more-dominant pasture mate. Then a bot fly larva chose that handy spot to burrow into George's flesh. A lump appeared. We didn't know what was causing it, but before we got around to calling the vet, the barn owner discovered that there was a bot fly larva inside and removed it. The lump went away - and hair started growing again. Now the bald patch is gone. Perhaps it was a coincidence.

Hair growing back a different colour

Bot fly larvae, when they burrow under the skin, secrete an anti-biotic which protects the host from infection at the site. We once found that a larva had burrowed into the neck of a pet rat; after the larva (huge compared to the rat's neck) was removed, the gaping hole healed up in record time, with no infection. 

So maybe those pesky little flies aren't all bad.