i6 THE POPULAR SCIENCE MONTHLY, 



of such a delicate and frail-winged fly to traverse the air to any great 

 distance. " On a calm, clear day, the latter part of last June, it was 

 my fortune to witness a closely-allied species {Phylloxera carycefolice 

 Fitch), of the same size and proportions, swarming on the wing to 

 such an extent that to look against the sun revealed them as a myriad 

 silver specula. They settled on my clothing by dozens, and any 

 substance in the vicinity that was the least sticky was covered with 

 them. With such a sight before one's eyes, and with full knowledge 

 of the prolificacy of these lice, it required no effort to understand the 

 fearful rapidity at which the Phylloxera disease has spread in France, 

 or the epidemic nature it has assumed. Imagine such swarms, mostly 

 composed of egg-bearing females, slowly drifting, or more rapidly 

 blown, from vineyard to vineyard ; imagine them settling upon the 

 vines and depositing their eggs, which give birth to fecund females, 

 whose progeny in five generations, and probably in a single season, 

 may be numbered by billions, and you have a plague (should there be 

 no conditions to prevent that increase) which, though almost invisible 

 and easily unnoticed, may become as blasting as the plagues of 

 Egypt.'- 



Since the above-quoted passage was written, I have fully proved 

 the same ability to fly in the winged grape-root lice, and am satisfied 

 that they can sustain flight for a considerable time under favorable 

 conditions, and, with the assistance of the wind, they may be wafted 

 to great distances. These winged females are much more numerous 

 in the fall of the year than has been supposed by entomologists. 

 Wherever they settle, the few eggs which each carries are sufficient to 

 perpetuate the species, and thus spread the disease, which, in the 

 fullest sense, may be called contagious. Whether in a state of nature 

 these winged females show a preference for any one part of the vine 

 in the consignment of their eggs, is not yet known. It is quite cer- 

 tain, however, that they do not reenter the ground. Neither do we 

 know whether — in the light of Balbiani's discoveries regarding the 

 European Oak Phylloxera — the young hatching from these eggs pro- 

 duce the diminutive sexual individuals already described. In confine- 

 ment I have had such eggs deposited both on the leaves and on the 

 buds, and from the preference which, in ovipositing, these aerial 

 mothers showed for little balls of cotton placed in the corners of their 

 cages, I infer that the more tomentose portions of the vine, such as 

 the bud, or the base of a leaf-stem, furnish the most appropriate and 

 desirable 7iicli. On this hypothesis it is quite possible for the insect 

 to be introduced from vineyard to vineyard, or from country to coun- 

 try, as well upon cuttings as upon roots. 



1 "Entomological Report of Missouri," vol. v., pp. 72, T3. 



