I have never been "comfortable" handling anything with poison on it, so I asked the internet a couple of questions about Raid.
First is Raid toxic to humans? - Answer: Yes, Raid roach spray can have detrimental effects on your respiratory health of you accidentally inhale it. The effects could be as simple as a painful repeated cough or you can suffer mild poisoning that requires medical attention. Do not put your hands anywhere near your mouth or nose until you wash the residue off them.
Second how long does Raid last on a surface? - Answer: Varied, but some say only two to four weeks.
So, I would ask myself "Why would I want to put something that might harm me on my horns, especially when with proper storage and handling I don't need to?
Always store horns with a stopper to keep the little critters from crawling inside. My observation after handling many bug eaten old horns is they like to be undisturbed and tend to eat from the inside out if they can. If you have powder in the horn, then through common sense you would presumably have to have a stopper. Two, do not store horns in the dark, in an environment where any type of natural fiber material is near. Such as cotton cloth, wool cloth, other clothing, wood fiber cardboard or wood boxes.
When you store horn away use an impermeable plastic bag such as a ziploc, or a plastic container like a rubber maid box or the like. Also, keep the horn in a room with well-regulated temperature and humidity such as on the wall, on a table, etc. If you do these simple things no toxics or chemicals are needed. I have horns that have been stored in these manners for up to 64 years in my homes with no problems noted.
Hope these comments are helpful.
Art DeCamp