Spiders can be difficult to control. Different companies operate very differentally from one another. I have a 50 gallon tank in the back of my truck, and spray once a month. (chemicals effectiveness lasts about a month in good conditions...EI... no rain, some will try to tell you otherwise they are lying!)) I know other companies use back pack sprayers or BG sprayers (hand pump) I think this is a joke, and a waste of your money. Depending on your personal situations I firmly believe in dusting the heck out of crawl spaces, as this kills on physical contact NOT chemical, and it never goes away UNLESS it gets wet, and there is NO resistence. Bifenthrin works well on spiders, and is my preferred chemical for them. Fogging attic crawls is also a good option, as long as the fog can be contained.
I watch "Billy the exterminator" and am constantly shaking my head. The show gives people the impression that a exterminator comes in with a vac, and squirt bottle in one trip, and everything is fixed.......That is a BIG LIE! You don't get to see the follow ups of a true exterminator......can make my job hard at times.....false impressions!
Lots of people are scared of chemicals....and they should be respected. Termidor is a very widely used chemical used for ants, and more for termites.....active ingredients are...fripronil...same chemical that is used in control of fleas for animals....you will know it as frontline. Then there is Imidacolprid (sp?) It to is used like the first, and you would know it as Advantage. So, the fear people have is the not knowing what is being used.....and they may just be using it themselves. All chemicals (for the most part) are multi-use, and labeled under different names, but the active ingredients, are used in food (farm) home pest control go hand in hand......pest control 101!
One more thing try to stay away from the big companies, they have the name, and the turn over rate in employees to match. Try to find a local guy that takes pride in his work.....he will try ten times harder, he has to compete with the big names. He only has reputation to go on, NOT SOME BRAND NAME. Check around your town, and a few names will pop up, realestate offices can help with this too. Believe ME I know!
Brian