354 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



Experiment G.—MnBj hnn^red egg-masses kept outdoors the whole time, first com- 

 menced hatching March 2d, and continued for thirty-eight days thereafter. 



Experiment 7. — Many hundred pods kept indoors till December 15, and hatching from 

 November 28 up to that time, were then exposed, and continued to hatch whenever the 

 weather permitted, up to April 10. 



Experiment 8. — A lot of one hundred pods that had been hatching in-doors from Novem- 

 ber 19, were exposed to frost January 15, and brought in-doors again January 28, where 

 they continued hatching till February 10. Every one was subsequently found to have 

 hatched. 



Experiment 9. — A lot of one hundred under same conditions as in Experiment 8, up 

 to January 28. They were then exposed again and brought in-doors February 16, when 

 they commenced hatching and continued to do so till the 27th. All were found sub- 

 sequently to have hatched. 



Two important conclusions are deducible from the above experiments. 

 First: The eggs are far less susceptible to alternate freezing and thaw- 

 ing than most of us, from analogy, have been inclined to believe. Those 

 "who have paid attention to the subject know full well that the large 

 proportion of insects that hibernate on or in the ground are more injuri- 

 ously affected by a mild, alternately freezing and thawing winter than 

 by a steadily cold and severe one, and the idea has quite generally pre- 

 vailed that it was the same with regard to our locust-eggs. But, if so, 

 then it is more owing to the mechanical action which, by alternate ex- 

 pansion and contraction of the soil, heaves the pods and exposes them, 

 than to the effects of the varying temperatures. Second: That sus- 

 pended development by frost may continue with impunity for varying 

 periods after the embryon is fully formed and the young insect is on the 

 verge of hatching. Many persons, having in mind the well-known fact 

 that birds' eggs become addled if incubation ceases before completion, 

 when once commenced, would, from analogy, come to the same conclu- 

 sion with regard to the locust-eggs. But analogy here is an unsafe guide. 

 The eggs of insect's hibernate in all stages of embryonic development, 

 and many of them with the larvae fully formed and complete within. 

 The advanced development of the locust embryo, frequently noticed in 

 the fall, argues nothing but very early hatching as soon as spring opens. 

 Their vitality is unimpaired by frost. 



Experiments to test the effects of exposure to the free air, — The eggs in 

 the following series were obtained at Manhattan, Kans., in November, 

 and all under similar conditions : 



Experiment 26. — A large number of egg-masses were thoroughly broken up and the 

 single eggs scattered over the surface of the ground outdoors early in December. By 

 the 23d of February all had perished, and most of them had collapsed and shriveled. 



Experiment 27. — A large number of pods were partly broken up and exposed, as in 

 Experiment 26. On the 10th of March the outer eggs were mostly dead and shrunken, 

 but a few of the protected ones were yet plump, the embryon well advanced and 

 apparently sound. Placed in earth they subsequently hatched. 



Experiment 28. — A large number of unbroken pods-were exposed under similar con- 

 ditions as in the preceding experiments. By March 10 fully three-fourths of the eggs 

 had perished, and by April 1 all had perished. 



Experiment 29. — Fifty egg-masses were kept indoors in an open-mouthed bottle in 

 perfectly loose and dry earth from November 6. Fully eight per cent, of the eggs had 

 hatched by December 28, when hatching ceased, and a subsequent examination showed 

 the srest to have shrunken and perished. 



It is very evident from the above experiments that we can do much 

 more to destroy the eggs by bringing into requisition the universally 



