I have a bottle of concentrate, maybe 3 yrs old, been sitting on the shelf in garage. Does it lose its effectiveness with age? I've heard that sunlight will break it down. This bottle has been opened but kept mostly in the dark. Need to treat some clothes and my tent.

Martins, has no expiration date, not sure what brand you have, id still use it.

Yea its martins, google says maybe 5 yrs for most pesticides but not real specific

You could spray a hat or something similar, sit outside this evening and see how it goes with mosquitoes, at very least spray it around the back yard to use it up.

I believe ratio is 2oz to 1 gal for .5% if my math is correct. For clothes that is.

As long as it did not freeze in the garage it should be fine. If you think it may of froze , buy fresh.

Hadn't thought of that, it probably has froze. I guess I'll just spray it around the house and get a new batch for my clothes. Don't like taking chances on those nasty stinking little bloodsuckers.

Podunk: "Hadn't thought of that, it probably has froze. I guess I'll just spray it around the house and get a new batch for my clothes. Don't like taking chances on those nasty stinking little bloodsuckers."

I too let mine freeze last winter, didn't think about it until this thread.
I used it and only found 1 tick on me all year, I live in heavy tick country of NW Minnesota.

Per google search as long as it hasn't crystalized it should be okay and even then just shake it up to desolve it. Trying a test out in the backyard this afternoon. Looking for ticks on a Sunday afternoon.

I'd just use it up around the house (especially, around the base of the house, near standing water, windows, doors, doormats, and in the garage), and buy a new one to treat your gear.

Finally got a tick for expermint. Crawling up my leg pretty fast, put him on a permethrin treated hat, treated with old 10% concetrate diluted to .05%. Immediately didn't like it and fell off. Put him on a untreated hat, immediatedly started headen north. Put him back on treated hat, fell off. After a couple back and forths of this I think it died. Myth busted I say its good to use.

P.S. Just to be sure I cut the little bas##d in half.

We've been told by the chem reps that there isn't much that will mess with permethrin, especially just an expiration date. (used in row crop fields for insect control sometimes) Stored in totes outside over the winter, in the sun, etc. This is highly concentrated stuff most of the time but I'd assume the same goes for the store-bought goods.