202 TRANSACTIONS OP THE 



tunity for the systematic observation of the habits of the insect in this 

 climate, and for experiments with remedies and resistant vines, caused 

 the idea of the immediate extirpation to be abandoned in favor of 

 the experimejital use of the plot. It is hardly necessary to say that 

 ever since, a rigorous system of disinfection has obviated all danger 

 of the accidental transmission of the insect to uninfected districts. 

 The summary report of Mr. Morse, given below, shows the results of 

 this season's observations. — E. W. Hilgard.1 



OBSERVATIONS ON THE PHYLLOXERA MADE DURING 1884. 



It has been supposed heretofore that only a part of the recognized 

 forms of the phylloxera exists in California. This apparent diver- 

 gence from the natural habits of the insect has given direction to the 

 investigations which have been carried on at the University. 



A partial report on the forms found in our own vineyard plot was 

 published in the report of the Agricultural Department for 1882, and 

 may here be briefly summarized. It shows that the larvae, and a 

 small proportion of the wingless mother insects, pass the Winter in a 

 dull, lifeless condition, but are easily brought to life and activity by 

 a proper change in temperature; that the middle of April finds the 

 adult mother beginning to lay; and that soon after young larvse 

 are produced and scattered to all parts of the roots. The increase is 

 slow until about the middle of June. Shortly after, the larval form 

 with rudimentary wings appears, and by the first of July the winged 

 form is found fully developed. The eggs of the mother louse are 

 most abundant at the end of the same month, and at the same time 

 a decrease in the numbers of adult mothers becomes apparent; the 

 maximum number of larvae is also reached. Only a few eggs are 

 usually found after October, and very little action is noticeable after 

 November. The time of these changes, however, will vary greatly 

 with the season. 



In the laboratory it was found that a single insect produced seventy- 

 five eggs, laid frequently at the rate of five per day; some days none 

 at all were produced. Thirteen days are required to hatch them, and 

 seventeen more for the development into egg-laying mothers. 



The object of investigation since the above was published has been 

 toward determining the existence, habits, and movements of less 

 familiar forms. 



The late rains this Summer have stimulated a generous growth of 

 those finer roots on which the winged-form is produced in greatest 

 abundance. Around such roots were placed properly arranged "traps," 

 viz. : glass jars or bottles, partially buried in the soil. A rapid pro- 

 duction of the winged form was noted from the twentieth of August 

 to the beginning of September; some were developed as late as Octo- 

 ber tenth. As many as five eggs were laid by some of the confined 

 winged insects, before death; none of these eggs, however, were ob- 

 served to hatch, hence no sexual individuals were obtained. 



In arranging the glass-jar " traps " the soil was considerably loosened 

 up, and thus was prepared the way for the migration of the winged 

 insects, which occurred about the twentieth of August, when they 

 could be found in considerable numbers crawling about upon the 

 small lumps of earth, preparatory to taking wing. Only one was 

 actually seen to fly up to the vine, although others were found quietly 

 fixed on the under side of some of the leaves. This passing through 



