The excellent monographic studies of Brennan (1935) and Stone (1938) on Nearctic Tabanidae and the even more recent catalog of Philip (1947) has placed the study of this group on a firm foundation. The student of this family rarely suffers from a dearth of material since the abundance of individuals of many species, their ease of preservation and their economic importance lead to the collection of long series. As these series accumulate, it sometimes is found that certain species exceed the limits of variation conceded that species, and in other cases what appear to be new forms, may be separated.

In 1944, as soon as DDT became available, laboratory investigation of its possibilities for control of codling moth, Carpocapsa pomonella (L.) was started at Vineland Station. The work was later expanded and the methods improved until the present technique was evolved; this is still unsatisfactory in many respects but is presented to indicate what may be accomplished in a small laboratory with very limited personnel and equipment and at comparatively little cost.

In biological research it is often desirable to rear and handle animals free from microorganisms. This is particularly true in nutritional studies in which it is generally recognized that certain orgnisms in the digestive tract can supply nutritional factors which might otherwise be lacking in the diet. The possibility of this intervention makes it necessary to devise techniques for rearing and handling insects aseptically, in so far is the fauna and flora of their intestinal tract and of their environment are concerned. Consequently, a technique used throughout the present series of studies was developed making use of specially designed equipment by means of which nymphs of the cockroach, Blattella germanica (L.), were hatched and maintained under aseptic conditions, fed aseptic food, and kept aseptic throughout a series of measurements to evaluate their weight increment. The equipment and methods used constitute the basis of the present paper.

The spiders considered here were collected by Dr. Francis Harper during the period from May 31 to December 4, 1947, in the vicinity of Nueltin Lake, Keewatin, Canada while on a trip made under the auspices of the Arctic Institute with support from the Office of Naval Research.

A general account of the area and field notes have been given by Harper (1948, pp. 153-184) and Henry W. Fowler has presented a taxonomic report on the fishes (1948, pp. 141-152).

Eleven species of spiders belonging to five families are represented by mature specimens; and juveniles, not determinable to species, add another family.