The term 'itty-bitty biter' refers to two small insects, a MITE and a GNAT. A MITE is an arachnid that is usually less than 1 millimeter in size and can be found in soil, on plants, and in stored food products. A GNAT is a small fly that is typically less than 5 millimeters in length and can be found near water sources or in moist areas. Both of these insects are known for their ability to bite humans and animals, making them itty-bitty biters.