The term 'annoying little biter' can be summarized by two crossword solutions: 'NoSeeum' (7 letters) and 'GNAT' (4 letters). NoSeeums are tiny, blood-sucking insects that are found in tropical and subtropical climates. They are so small that they are often not seen, hence the name. Gnats are also small flying insects, but they do not bite humans. They are usually found in areas with a lot of moisture, such as near ponds or streams. Both NoSeeums and Gnats can be very annoying, especially when they fly around people's heads.