OF THE STATE ENTOMOLOGIST. 33 



on the inferior results which attended the infancy of those industries 

 in America. Such, in brief, is the history of the grape Phylloxera. 

 Let us now take a closer insight into the nature of the insect. 



The genus Phylloxera is characterized by having three-jointed an- 

 tennas, the third or terminal much the longest, and by carrying its 

 wings overlapping flat on the back instead of roof-fashion. It belongs 

 to the whole- winged bugs {Ilomoptera)^ and osculates between two 

 great families of that sub-order, the Plant-lice {Aphididce) on the 

 on.e hand and the Bark-lice (Coccidce) on the other. In the one- 

 jointed tarsus of the larva or newly-hatched louse, and in being al- 

 ways oviparous, it shows its affinities with the latter family, but in the 

 two-jointed tarsus of the more mature individuals, and in all other 

 characters, it is essentially aphididan. '"In every department of nat- 

 ural history a species is occasionally found which forms the connect- 

 ing link between the two genera, rendering it doubtful under which 

 genus it should properly be arranged. Under such circumstances the 

 naturalist is obliged to ascertain, by careful examination, the various 

 predominating characteristics, and finally place it under the genus to 

 which it bears the closest affinity in all its details." So wrote Audu- 

 bon and Bachman twenty-eight years ago ;* and what is true of gen- 

 era is equally true of species, families, and of still higher groups. In 

 the deepest sense all Nature is a whole, and all her multitudinous 

 forms of animal and vegetal life are so closely interlinked, and grad- 

 uate into each other so insensibly, that in founding divisions on too 

 trivial differences we subvert the objects of classification. Thus, in- 

 stead ol founding a new family for this insect, as Dr. Shimer did, and 

 as there seems a tendency on the part of others to do, it is both more 

 consonant with previous custom, and more sensible in every way, co 

 retain it among the Aphididce. 



BIOLOGIC AL. 



Different Forms which the Insect Assumes. — Not the least in- 

 teresting feature in the economy of our Phylloxera, are the different 

 phases or forms under ^hich it presents itself. Among these forms 

 are two constant types which have led many to suppose that we have 

 to do with two species. The one type, which I have, for convenience, 

 called gallcecola^ lives in galls on the leaves ; the other, which I have 

 called radicicola^ on swellings of the roots. The subjoined table will 

 assist to a clear understanding of what follows: (li) 



Type 1. GallfKcola. — {VUifolur. Fitch ; Fio', 4,/, g, h.) 



Type 2. Radicicola — 



a, Degraded or Wingless Form. (Fig. .">, c, /, g.) 



[i^ Perfect or AVingedForm. (Fig. G, g^ h. Fig. 8, b.) 



* Quadrupeds of North America, vol. i., p. 215. 



