FIELD BOOK OF INSECTS. 



adults) may have appeared in 1911; its next appearance 

 would be 1928. Another might be 1916, 1933, and so on; 

 while the third might be 1919, 1936, and so on. As a 

 matter of fact, these are actual broods although they may 

 not be the ones of your neighborhood. However, the 

 example shows that we may have Seventeen-year Cicadas 

 oftener than every seventeen years, to say nothing of the 

 possibility of laggards or extra-spry individuals, in the 

 various broods, which do not appear on schedule time. 



There are numerous other species of this family. It 

 might be noted that the name Cicada tibicen, of many 

 books, as applied to one (or all !) of our Harvest-flies, is an 

 error, Cicada tibicen probably being a tropical species. 

 The differentiation of species is based largely on the form 

 of the male genital plates, although there are size- and 

 color-differences and an attentive ear can detect differ- 

 ences in song. Of the genus Cicada (as now limited, = 

 Tettigia), the small hieroglyphica (Plate XXII), with an 

 almost transparent abdomen, may be found in pine 

 barrens, and is our only species. Plate XXII also shows a 

 common species of Tibicen which is fairly typical of its 

 genus, the common one in our region. The somewhat 

 similar Okanagana is more common in the West than with 

 us. 



MEMBRACID^E 



The Tree-hoppers have been aptly called Insect Brownies. 

 If you doubt the aptness see Plate XXIII or, better, look 

 at a number of species, full in the face, through a low- 

 power lens. The prothorax is variously modified and, in 

 some of the tropical species, the modifications are very 

 extraordinary. The young differ from the adults in being 

 more normally shaped. Many of these young and some 

 of the adults excrete "honey-dew," much as aphids do, 

 and are eagerly attended by ants for the sake of this fluid. 

 All of the species suck plant juices and the eggs are usually 

 laid in the tissues of the food-plants. They are called 

 Tree-hoppers because most of the species live on trees and 

 low bushes, hopping vigorously when disturbed. They 

 are best collected by beating them into an upturned 



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