44 GRAPE CULTURE AND 



cations of the Agricultural Department, the whole of which, 

 with additional observations made since, are here arranged in 

 a somewhat modified form. 



The observation was taken up immediately after the discov- 

 ery of the insect, the object at first being simply to study the 

 more prominent types here, in order to become familiar with 

 the prevailing forms generally known to exist in other vine- 

 yards; and, also, to note any special habits wherein they 

 might differ from those observed in other countries. No 

 special attention was originally intended to be given to the 

 prosecution of new investigations tending toward the settle- 

 ment of disputed points regarding the biology of the insect. 



No stated time was set apart for this work, which has at 

 all times been carried along in conjunction with other Uni- 

 versity duties. The available apparatus, too, has not always 

 been all that could be desired for obtaining thorough and 

 complete results. 



At the outset, only one form of the insect was recognized, 

 but as the work advanced, new and unfamiliar forms continu- 

 ally appeared, until we have, by a happy coincidence of 

 special fitness of vine varieties and surroundings, witnessed 

 the production of most of the forms known to foreign inves- 

 tigators. 



The importance of such a line of investigation, under such 

 circumstances, becomes apparent, when we consider that 

 among the various forms which the insect is capable of 

 assuming only a part, and these of the forms which are least 

 easily spread, have thus far been seen in appreciable numbers 

 in California vineyards. A solution of this apparent diver- 

 gence from the habits of the insect, as observed elsewhere, 

 gives direction to the investigations which have heen car- 

 ried on. 



