Insects as a group occupy a middle ground in the biosphere between bacteria and viruses at one extreme, amphibians and mammals at the other. The size and gen eral nature of insects present special problems to the student of entomology. For example, many commercially available instruments are geared to measure in grams, while the forces commonly encountered in studying insects are in the mil ligram range. Therefore, techniques developed in the study of insects or in those fields concerned with the control of insect pests are often unique. Methods for measuring things are common to all...