Any Ivermectin dewormer will get bots. Some of the other parasites (like Ascarids) are becoming resistant to Ivermectin, but it still seems very effective for Bots.
We always deworm at least twice for Bots. We use it once in December when we have had some hard freezes to kill all of the Bot Flies and then use it again in February to get any that were not in the right stage in December. I really think the FEbruary deworming is more effective.
If you do not remove all of the eggs on their legs (and other places), you will kill Stomach Bots way up into spring -- like May.
Added -- You can get just as good a kill from using the injectable Cattle Ivermectin. DO NOT inject it. Just squirt it in the back of a horse's mouth with a 12cc syringe. We have so many horses that I buy the 1000cc bottles of Ivomec injectable and it costs less than $2.00 per horse. DO NOT buy Ivomec Plus --- Just buy any plain injectable Ivomec for cattle. We use it at a rate of 1cc per 100# of horse. It is the exact same active ingredient as Zimecterin or any other plain Ivomec labeled for horses.
Last edited by Cherie; 09-20-2011 at 10:03 AM.