226 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



the eggs of (Edipoda pJiancecoptera and Acridium Americanum, and in 

 these species the cement which binds the eggs together is more copious 

 than in the others.^^ In one narrow-bodied species (JEucoptolophus sord- 

 idus) the eggs are arranged in but three rows. 



Even in the pods of those species which have the eggs Irregularly 

 arranged the head ends point either mostly outward (differentialis) or 

 inward {Americamwi), so that the young locusts may either push out at 

 the sides or through a central space. 



The length of the neck, or that portion containing no eggs, varies not 

 only in different species but in different masses of the same species. 



DOES THE FEMALE LAY MORE THAN ONE EGG-MASS? 



This is a question often asked, but which the average farmer has no 

 means of definitely answering. " It is the rule with insects, particularly 

 with the large number of injurious species belonging to the Lepidoptera, 

 that the eggs in the ovaries develop almost simultaneously, and that 

 when oviposition once commences it is continued uninterruptedly until 

 the supply of eggs is exhausted. Yet there are many notable excep- 

 tions to the rule among injurious si)ecies, as in the cases of the common 

 Plum-curculio and the Colorado potato-beetle, which oviposit at stated 

 or irregular intervals during several weeks, or even months. The Eocky 

 Mountain locust belongs to this last category, and the most casual ex- 

 amination of the ovaries in a female, taken in the act of ovipositing, will 

 show that, besides the batch of fully -formed eggs then and there being 

 laid, there are other sets, diminishing in size, which are to be laid at 

 future periods. This, I repeat, can be determined by any one who will 

 take the trouble to carefully examine a few females when laying. But 

 just how often or how many eggs each one lays is more difficult to de- 

 termine. With spretus I have been able to make comparatively few 

 experiments ; but on three different occasions I obtained two i)ods from 

 single females, laid at intervals of eighteen, twenty-one, and twenty-six 

 days, respectively. I have, however, made extended experiments with 

 its close congeners, femur-riibrum and atlanis, and in two cases, with 

 the former, have obtained four different pods from one female, the lay- 

 ing covering periods of fifty-eight and sixty-two days, and the total 

 number of eggs laid being 9G in the one case and 110 in the other. A 

 number of both species laid three times, but most of them — owing, per- 

 haps, to their being confined — laid but twice." 



Yersin concludes, referring to the European migratoria, that eggs are 

 laid thrice, at intervals of about a month, while Kriinitz, Keferstein, 

 and Stoikowitsch^^ also declare that they are laid in three different 

 masses. Professor Whitman, in his 1876 experiments, had a female 



63 The species occurrin<i around Saint Louis in the e^gs of wL-c'l we have noticrd the same quadri- 

 linear arrangement as in thoa^ of spretus, rr-^, asV^e from thoseslrcarly meutioncd Calopteniis b.vittatus, 

 PezotettLXviolz,P. uaicolor, Chrysocraon viridiSy Tragoccphala viridi/asciata, (Edipoda Carolina, CE. sul- 

 /urea, and E ucoptolophus costalis. 



3* See Koppen, p. 36. 



