142 Annals Entomological Society of America [Vol. XIII, 



3. THE LIFE CYCLE IN HEMIPTERA 

 (ExcL Aphids and Coccids.) 



By E. D. Ball. 



The life history of any insect if carefully and conscientiously 

 traced, wiil show many and striking adaptations. These in the 

 aggregate will be found to display a marvelous adjustment to 

 and harmony with the environment. The life cycle may be 

 long or short, occurring early or late, the generation one or 

 more and the winter passed as egg, nymph or adult, according 

 as these variations adapt the insect to its individual niche in 

 the scheme of things. 



In the main these adaptations are not, however, mere 

 adjustments to a temporary excess of heat or cold, moisture 

 or dryness, but rather are deep-seated and fixed modifications, 

 brought about through reaction to seasons unnumbered whose 

 means, at least within the limits of the present geological 

 period, are constants. Such adaptations as these are not to be 

 overthrown by the influence of an early season or a late one, a 

 heavy rainfall, or even an arid condition. They are merely 

 modified in detail, but these modifications only serve to empha- 

 size the fixity of the underlying principle. The man who wrote 

 "The number of generations a year will vary in different parts 

 of the country according to the various climates and is likely 

 to fluctuate from year to year in accordance with seasonal 

 variations" was so impressed with trivial details that he entirely 

 missed the great concept of nature's plan whereby each and 

 every species exists as a species primarily because it has through 

 the ages become differentiated and adapted to its humble place 

 in the structure of life. His concept of nature is that of the 

 thistledown blown by the wind while the reality is the majestic- 

 elm bending and waving in every passing breeze but which in 

 the end remains firm and upright. 



Commencing with the Cicadid^ as probably the lowest type 

 of the field assigned, we find a marked uniformity in their life 

 history in that all the species pass the winter as nymphs and 

 all have an under-ground habitat, coming out as adults with 

 marked uniformity in the middle of the summer. Beyond that,. 



