I work in pest control and 99% of the shit we use. You can buy without having a license. The license just covers us to use the products on other people's houses responsibly. If you really want to do pest control, you only need a few chemicals and they are all easily obtainable on Amazon.
-demand CS (very strong can burn skin)
-talstar p (better during cold months)
-Archer (good for roaches)
-Alpine wsg (water soluble granules) - 1oz per gallon
Advion WDG (water dissolvable granules) similar to Alpine.
Flea/tick control
-precor (spray can)
-cimexa (dust)-good for weep holes around exterior of home too.
PT flea and tick control (spray can)
Ants
-intice 10 granules (sprinkle around the perimeter of the home)
-maxforce gel
-the above mentioned chemicals
Terro ant bait is a gimmick
Spiders
-onslaught Fastcap (great shit for spiders and scorpions)
We have a persistent weevil problem (at least I think they're weevils, they were concentrated in an old bag of flour in the back of a cupboard), is there anything you know of that can wipe em out? We've containerised our cupboards and make efforts to keep surfaces free of, yknow, weevil food, but so far they're resistant to starvation. Vinagre seems to help... a bit.
Talstar p will kill them as well as the archer. You need an insect growth regulator. Treat the infected food and throw it out. Then treat your whole pantry/kitchen. The precor will also work.