@EggSighted4Life I have ordered the Martins ready to use spray, do I use it the same way as the Fly Rid? Just a spritz below the vent.... etc. thanks for this BTW, I have a new lice infestation that I want to quash ASAP.
Is it this one? Yes I would treat in the same manner. I did see on one of the sites I was looking at this just now that it stated not to use on animals under 12 weeks old. If it says that on my other product I must have missed it and have used for more than 2 years on younger birds without issue.
No, I don't worry about spraying the eggs sacks. The lice will hatch and crawl onto the skin where the residual and/or retreatment will handle them. Only thing I haven't figured out yet is if the hatched egg sacks still stay attached even though there is nothing in it or they are dead. I mean they are glued on so I don't THINK they just fall off or disappear... either before molt or without picking them off.
In fact, drawing from personal experience... I'm gonna say NO the egg sacks will NOT disappear. When my daughter was a babe, I always oiled her hair. Once I saw the gleaming beads about an inch away from the scalp. She had caught lice on a trip to my sisters, and I didn't realize it but the regular oil applied either killed them or made the original offender go away. Grown out over an inch they were definitely dead per our family practitioner, but I still had to get the dead eggs out using a lice comb....
I'm so used to talking about poultry lice, it don;t even make me itch anymore.

(scratch my head)
BUT by paying attention, you should be able to tell if your issue is still active or has been taken care of, by the quality of skin and such. There are other sign aside from just the nits.
I did go to my local feed store this morning and this is the ONLY thing they had so I thought I would give it a try.
It's usually in the equine section... But I would probably go ahead and try that. If it seems ineffective, return it for a refund and look elsewhere for a permethrin product.
