INSECTS 



was at its height, and the eggs are now due to hatch almost 

 any time. When studying the cicadas of Brood X near 

 Washington in 1919, the writer found the first evidence 

 of hatching on the twenty-fourth of July. Perhaps the 

 normal time of hatching had been delayed somewhat by 

 heavy rains that fell almost continuously during the ten 

 days previous, for many eggs examined during this time 

 were found to be dead and turning brown, though the 

 percentage of these was small. The twenty-fifth was hot 

 and bright all day. The trees were inspected in the 

 afternoon. Their twigs had been bare the day before. 

 Now, at the entrance holes of the egg nests were little 

 heaps of shriveled skins, thousands in all, and each so 

 light that the merest breath of air sufficed to blow it off; 

 so, if according to this evidence thousands of nymphs had 

 hatched and gone, the evidence of as many more must 

 have been carried away by the winds. An examination 

 of many egg nests themselves showed that over half con- 

 tained nothing but empty shells. Whole series were thus 

 deserted, and usually all or nearly all, of the eggs in any 

 one series of nests would be either hatched or unhatched. 

 But often the eggs ot one or more nests would be un- 

 hatched or mostly so in a series containing otherwise only 

 empty shells. Delay appeared to go by nests rather than 

 by individual eggs. 



As a very general rule the eggs nearest the door of an 

 egg chamber are the ones that hatch first, the others 

 following in succession, though not in absolute order. 

 But unhatched eggs, if present, are always found at the 

 bottom of the nest, with the usual exception of one or two 

 farther forward. Only occasionally an empty shell occurs 

 in the middle of an unhatched row. I f the actual hatching 

 of the eggs is observed in an opened nest, several nymphs 

 are usually seen coming out at the same time, and in 

 nearly all cases they are in neighboring eggs, though not 

 always contiguous ones. So this rule of hatching, like 

 most rules, is general but not binding. 



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