Could it be Galactic Adventures?
One thousand of each type should suffice to clean out our Zwargs' nest for us. Half-an-hour later, Zebekee's preparations were ... Screeching with fury, the Zwargs fought ferociously as their stronghold was invaded on all four sides. .. [from here]
The Google Books page has no bibliographic info (except for a 1980 pubdate). The ISFDB page says it was published by Rand McNally in 1980 (and has a different cover).