REPORT OP COMMITTEE ON PUBLICATION 181 



most important injury is done in midsummer when the insects congregate 

 in large numbers in the grape clusters. The presence of the insects them- 

 selves together with the honey dew which is secreted by them, renders the 

 cluster unsightly and unattractive and also makes the berry much more 

 susceptible to decay infections. 



The only remedy which seems feasible at present is to take off and burn 

 all of the loose bark of the vine during the winter season and afterwards 

 spray the vines thoroughly with distillate emulsion. 



PHYLLOXERA IN CALIFORNIA. 



By R. L. NOUGARET, 

 United States Bureau of Entomology, Walnut Creek, California.* 



Phylloxera vastatrix Planchon. 



The Bureau of Entomology of the United States Department of Agricul- 

 ture, for the past few years, has been making an investigation of the grape 

 phylloxera under existing California conditions. This work is about con- 

 pleted, and a report on the results of this investigation, which is being con- 

 ducted by Mr. W. X. Davidson and the writer, will shortly be published. 

 This paper, in abbreviated form, presents such extracts of this report as are 

 of interest, considered from a viticultural viewpoint. 



The difference which apparently seems to exist in the degree of injury 

 caused to the vineyards of California, compared to that which affected those 

 of Europe, prompted this investigation. In France the devastation of vine- 

 yards progressed uninterruptedly. Once infested, the vines died in a short 

 time. The spread of the insect w r as alarmingly rapid in its course from 

 one vineyard district to another, and mostly due to its natural habit. In the 

 course of twenty-two years' time, from 1863, when the phylloxera's injury 

 was first noticed, to 1885, the infestation had spread over an area of one 

 million hectares (approximately two million and a half acres), a good portion 

 of which was completely dead. In California the great boom in vineyard 

 planting, which occurred from 1880 to 1883, was chiefly responsible for the 

 spread of the pest by vines being used from infested vineyards for planting 

 out the new ones, rather than to the natural spread of the insect due to its 

 biological traits. The affected vineyards also differ essentially, inasmuch 

 as the vines withstand the injury for a much longer time than vinifera 

 varieties did in France. It is not uncommon to find in California vineyards 

 known to have been infested fifteen or twenty years and still bearing crops 

 that justify the expense of cultivation. The vines comprised in the char- 

 acteristic "oil spot," or primarily infested area, gradually become stunted in 

 growth, then cease bearing grapes, or the very few produced are worthless, 

 but continue for years to put forth a stubby growth before dying. The 



* Published with the permission of the Chief of the Bureau of Entomology. 



