The term 'Nasty Insect' can be summarized by two crossword solutions: HORNET (6 letters) and WASP (4 letters). Hornets and Wasps are both members of the Vespidae family, which includes over 200 species of wasps. Hornets are larger than wasps and have a more aggressive behavior. They are also capable of delivering a painful sting. Wasps are smaller than hornets and are usually less aggressive. They are also capable of delivering a painful sting, but not as powerful as a HORNET's.