The Effect of DDT on the Mid-Gut of the Bee

The mid-gut from twelve bees poisoned with the pure para isomer of DDT was studied. Of these, five contained the large bubble of gas described on page 48: their histological appearance was almost identical but it differed in some ways from those which contained no bubble.

The research program of the Division of Entomology is steadily evolving as surely as are the insects themselves. The broad outlines of today's program have been shaped through the years by central administrative policies, by the nature and significance of the problems encountered, and by the pressure of public demand; the detail has been affected primarily by the availability of trained staff and research facilities, by the quality of local leadership, and by pertinent developments in sister sciences. All of these are continuing influences, which, together with important recent developments and some weighty unpredictables, will determine the nature and scope of tomorrow's program. But certain trends in research seem clear. The subject is discussed under three main headings, with a final summarizing statement.

In many parts of the St. Lawrence drainage system, enormous numbers of Trichoptera, often mingled with Ephemerida, emerge during the summer and become a pest in a considerable zone bordering the water. The insects swarm in open areas, especially around trees and lights, invade houses, settle in large numbers on walls and other surfaces, ruining those that have been freshly painted, and pile in decaying and odoriferous drifts along the shore line. In addition, they give rise to a medical problem by evoking allergic reactions in hypersensitive individuals.

Investigations begun in 1947 in Saskatchewan have provided new data on the life-history and habits of the black fly Simulium arcticum Mall. The only published account of the biology and egg-laying habits of this species is that by Cameron (1922). He states that the eggs are laid in the usual black-fly fashion, i.e., attached in masses to rocks wetted by sprav in river rapids. The evidence here reported, however, indicates that the eggs are laid singly over the surface of flowing water and that these eggs settle and beconie embedded in the sand on the bottom. The investigations have conclusively shown that the species over-winters in the egg stage. These facts, important in an understanding of the biology of the species, are of particular value in planning a sound program of control.