There is a difference in all the critters discussed in this thread so far.
Wasp's - Mostly back, but some have yellow or blue on them. About an inch to an 1.5 inches in length. Generally not aggressive until you are within 2-3 feet of the nest. They will generally leave you be if disturbed if you get 15 feet or so away from the nest. They build little white colored nests under the eves and in out of the way places up high. The nest is somewhat like a honey comb and is usually not bigger than a softball. There is usually no more than 5-12 wasp that use one nest. There is a red variety that is more aggressive and bigger. Up to 2 inches and they mean business. I am not allergic to stings but one of the red ones got me on the jaw bone once . Man that swelled up for a week and hurt like Hell.
Yellow jackets are yellow and black. .75 to an inch or so in length. These are the only bee that can sting multiple times. They are very aggressive when disturbed. Been stung by them numerous times. Ran around my house three times once to get away. My dad hit a nest with a dozer once. I was about five riding with him. Bailed of and left it running ran clear across a field stripping clothes as we went (They will get to you wherever thy can) . They build colony type nests in depressions or hollows in the ground or under old stumps. They also will build nests inside the eves of houses, just about anyplace there is a 10 inch or so hollow place. If you find them in the ground, put gas on the nest. usually does the trick.
Mud Dobbers are generally black or brown. Not aggressive. dang near have to sit on one to get stung. Loners. make the aggravating mud nests you find in light fixtures or your bus you use for storage.
Hornets - About the meanest of the mean. They are large and can kill a child. They will hunt you down. Has one of the most painful stings. They build large nests that generally hang from a tree limb. The nest is generally the size of a basketball and grayish in color with an opening at the bottom. Yellow and black. I have seen some of these reach 2 inches in length. I have also seen many nests built under the eves of old houses as well. They usually will not bother you if out and about by themselves, but disturb the nest and you better beat feet for water or an enclosed space where they can't get to you.
Kind of rambled there but there you have it.
i know this is off topic but I'm hoping someone will be able to suggest something. I have a vinyl sided house and I have an area where I keep seeing wasps go in and out,I bought this wasp spray foam and it just fills the area up then melts. I have managed to kill a few but when I spray it they seem to climb out a different part of the siding. does anybody have any ideas of how to kill the wasps(they are about 8' off the ground) I can see no visible nest. any help is appreciated russ