Can someone tell me what the pest control company is injecting into my ';tubes-in-the-wall'; system?

I've watched them when they come out to the house, all they use is a simple pump-up sprayer available at any hardware store. What I'd like to know is what they're pumping in. Also a neighbor says that the pest control company ';owns'; the little access box attached to the house, and that I risk legal trouble if I open it and service the tube system myself, how can that be true?Can someone tell me what the pest control company is injecting into my ';tubes-in-the-wall'; system?
Why don't you call the pest control company and ask them? They're the only ones that can tell you for sure. Anybody on here is really only guessing.