This will take care of lice, mites and worms.
Head down to the Fleet Farm store and get some Liquid Ivermectin. Put 2-3 drops on each of your chickens on the back right between the wings. This will kill mites, lice and round worms. It will prevent heart worm but not cure an infestation.
While you are there look for Rotenone, you might get lucky. Don't count on it. If no luck, head to E-Bay and order several pounds. When it arrives put a pinch on the vent of every bird. Next find their dusting holes and put a teaspoon full of Rotenone in each hole. They will dust themselves. Renew after it rains. I like to put just a little in the coop on the floor along the walls. Gets the climbers.
Now just to clean things up real good and make sure everything is gone get a can of Cooking Vegetable Oil Spray like 'PAM' or better the cheap generic brand, you won't be eating it. Spray the perches real good with the cooking spray making sure to get the bottoms. The underside of the perch is where leg mites hang out. The cooking spray penetrates the cracks in the wood very well and will kill the mites hiding there. With luck the chickens will still be able to get a grip and won't end up hanging upside down like bats all night.
I do this every Fall when NPIP testing so I know my birds are very clean and healthy for the Winter. This treatment can be used any time of the year. The Rotenone is very effective in the dusting holes, it will save you a lot of work if you have a lot of birds. I hope this helps.
Warning: If you have a collie dog do not let it anywhere near Ivermectin. It will drop them dead on contact.
Edited by staff