W. E. Britton.
The Prevalence of Macrosargus cuprarius Linn. in the United States.
Psyche 22:26, 1915.

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26 Psyche [February
suggested as the retarding factor since the eggs were in a rather dry place compared with that in which they are usually laid and it has been found that eggs in the laboratory must be kept in a moist atmosphere to insure the emergence of the larvae. Of the thirty-five batches placed in direct sunlight none hatched, but eighteen developed up to the hatching point. Twelve batches showed no signs of hatching at the end of the eighth day. Five of the batches were either blown away or destroyed by some ani- mal. The only animals that could possibly be responsible for the disappearance of these eggs were birds or large insects, but whether or not they were responsible was not determined. EXPERIMENT 11.
On June 15, a beetle jusL about ready to deposit eggs was placed on a plant in the garden and enclosed by a glass jar. Within two hours she laid a batch of thirty eggs. Part of these were taken to the laboratory where they hatched in six days (June 22). The leaf to which the rest of the eggs were fastened was bent over and held in place so that the rays of sunlight would strike the eggs. At the end of twenty-four hours four of the control eggs and four of those left on the plant were fixed. Sections of these eggs show that development proceeded in both groups at the same rate and that sunlight had no visible influence upon the devel- opment of the eggs subjected to it. Another group of four were taken from the plant at the same time and kept in the laboratory in a moist watch glass. These hatched in the normal period (six days). Sunlight acting upon the fresh eggs for a period of one day had therefore no effect upon the development of these embryos. The eggs on the plant in the sunlight should have hatched on June 22. On this date the larvae within them could plainly be seen; they failed to emerge within the next two days when the experiment was concluded.
General Conclusions.
These experiments prove that the eggs
of the potato beetle in various stages of development are pre- vented from hatching when kept in direct sunlight, but are not retarded in their development. The non-hatching of these eggs is probably due to partial dessication. The advantage of conceal- ment is not so great therefore as that secured by shielding the eggs from the dessicating properties of sunlight, since the potato beetle



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