Numerous studies have shown that the cuticle of insects is complex and highly-differentiated and that the complexity varies from species to species (2, 8, 11, 13, 14, 17, 18).

The object of this study is to determine cuticular relationships between the grasshopper, Melanoplus bivittatus, and other insects already studied. This work was carried out by means of chemical tests and permeability measurements on fresh material rather than by methods of fixing and sectioning.

In a previous communication of this series (4), some general properties of the epicuticle of the two-striped grasshopper Melanoplus bivittatus were deduced from permeability measurements and chemical tests under various conditions. Among other things, it was found that the epicuticle is covered by a lipid layer, which regulates the rate of permeation of moisture through the cuticle. Because it has already been shown (2, 17, 21, 23, 24) that the rate of evaporation from the cuticle of several insects is a function of temperature and age, a study was undertaken of the effect of these factors upon the transpiration through the cuticle of grasshoppers in various instars.

It has now been well established that the cuticle of many insects is covered by a discrete layer of lipoidal material. Ramsay (26), Wigglesworth (32), Beament (4), and others have shown that the rate of evaporation-temperature curves from insects are characterized by breaks occuring at a “critical” temperature. In the previous paper of this seriis, Chefurka and Pepper (8) have shown that the rate of evaporation-temperature curves from Melanoplus bivittatus show a transition region from approximately 43 to 50°C.

It cannot be disputed that in any attempt to control populations of useful or harmful insects a knowledge of their ecology is of prime importance. In view of the significance of the various relationships between man and insects it follows that insect ecology should be a vigorous and strongly supported phase of entomology. It is the purpose of this discussion to consider briefly the present status of insect ecology and its relationship to ecology in general, and particularly to call attention to those characteristics of insect life that would seem to justify special treatment of insects from an ecological standpoint.

During studies of the parasite complex of the spruce budworm in the Lake Nipigon region of northern Ontario from 1946 to 1950, data were obtained on certain host-parasite relationships. The data were derived from two sources: the rearing each year of periodic collections of spruce budworms, and the dissection of budworm larvae and pupae that were collected and preserved at 2-day intervals during June of 1948 and 1949. The particular features investigated were: the sex ratio of parasites and its possible relation to the sex of the host; and the effect of parasitism on the apparent sex, rate of development, and size of the host.

Occasions frequently arise in laboratory work when it is necessary to insulate a delicate piece of apparatus, such as a sensitive balance, from vibration. Various tables designed to eliminate vibration have been described (anonymous). Most of these tables require the attachment of iron supports to a load-bearing wall or the sinking of a support into bed rock. Occasionally the building construction or the type of underlying strata, or both, make such methods of mounting ineffective. The instrument stand shown in Fig. 1 requires no attachments. It consists of rigid table 34 inches high, 30 inches wide, and 18 inches deep. The legs are made from 4 × 4 inch lumber sheathed with cluarter-inch plywood to form hollow sides; these sides are loaded with lead shot, steel stampings, or any other easily handled, heavy material. When loaded, the table weights can easily be rembved through openings at the tops of the hollow sides, under the cover.