You have to go to a feed store to get it. You can't get it at Home Depot or Lowes. I only used a half teaspoon on the last nest check, dumped just inside the doorway of each gourd. I used it prior to seeing any mite infestation. The martins walk on it and spread it around. Haven't seen one mite this year, for the first time ever. My number of jumpers have decreased drastically. I read that it will work on blow fly larvae also. Good stuff.
I have used it in the past with excellent results. It says on the label that you can sprinkle it directly on the birds (chickens and also barn yard animals) which makes me think it will work really well and be safe for the Martins if you sprinkle on the nest and in the corners of the compartment. This year I have been using carbaryl and it seems to be working well so far, but I am more careful about treating the nests with babies.
If you are placing this in the entrance and letting adults track it inside, likely they are getting directly onto bare, thin skin of young not yet feathered. It's my understanding that permethrin does not deteriorate as quickly as carbaryl when exposed to humidity -- not a good thing -- and I'd be very concerned about poison effects on baby birds. Just because the canister says safe on poultry, I'd not expose directly to baby birds, personally. Suggest just putting a tiny bit, maybe 1/4 teaspoon, into corners of nests when baby birds are 10 to 15 days old.
I have drainage holes in the bottom of each nest. If I put it at the bottom of each nest, most would leak out in my opinion, especially since gourds swivel. Each time a martin steps in it, I imagine a powdery residue clouds all over the nest. This method treats the adults and chicks. The fact that it doesn't deteriorate fast is a good thing in my opinion. When the next generation of mite eggs hatch, the permethrin would still be functional and destroy the next generation of mites. So no retreatment is necessary. My martins will be mite free at least until the mingle again with those from other colonies. All my chicks are healthy, normal, and fledging. I've had nothing but a good experience with this stuff. I lost a lot more chicks last year due to early jumping, because I wasn't treating mites as effectively.
