55 



very large number of dead flies were found under the shells of black scale, more so 

 than during any other time of this investigation. Cause unknown to me. 



February. — The larva and pupa of the insect in question w T ere rarely found during 

 the weekly investigations of this month. Flies were abundant upon the foliage of 

 citrus trees and upon the stems of chili peppers during most of the bright sunny 

 days of the past month. The mortality of adult flies under the scale continues, but 

 not so apparently as during January. 



"Length of time of a generation under natural conditions." I have but one posi- 

 tive record of this. On August 14, 1903, I liberated a colony of S. cyanea (flies) on 

 the premises of G. A. Lindsay, Long Beach. No Scutellista had been placed previous 

 to this nearer than 4 miles away. I w r as in a position to watch the progress of this 

 colony closely. I soon saw by the color and appearance of the scale (L. olease) that 

 they were parasitized. On October 8, 1903, I was investigating the progress of the 

 parasites and upon removing a full-grown black scale, a. fully developed Scutellista 

 emerged from the shell into my hands. This makes fifty -five days from the time the 

 flies were liberated and the first appearance of the adult of the next generation. 



On October 18, 1903, I found a large quantity of horseweeds in a gulch to leeward 

 of a lemon orchard in which S. cyanea had been placed. These were found to be 

 covered with black scale (L. olease) . Upon investigation it was found that the scale 

 was extensively parasitized, at least 50 per cent; upon a piece of horseweed 16 inches 

 long I removed 80 black scale; 42 of these contained parasites, the majority being 

 S. cyanea. 



On October 19 I cut these weeds into short lengths, placed them in fruit jars, 

 covered the tops with lawn and distributed them in the different citrus orchards. 

 The owners agreeing to liberate such flies as emerged once every twenty-four hours. 

 On December 18 flies w r ere still issuing from the weeds placed in one of these jars. 

 Later on this jar was removed to the office in Los Angeles, and the commissioners 

 informed me that flies (S. cyanea) continued to emerge up to the ninety-seventh day 

 after being placed in the jar. These weeds were mature when placed in jar, and the 

 scale upon them was fully developed. 



The points of greatest interest shown in the notes above quoted are 

 that at the height of the breeding season (in August and September) 

 the life C} T cle of this insect is about fifty-five days, and that during the 

 colder season of winter these insects, as already indicated in my own 

 notes, enter a period of semihiber nation which may extend over a 

 period of three months. The bearing of these facts on the usefulness 

 of this parasite is very apparent. The feature of greatest anxiety was 

 how it would pass the winter season during which, in the case of mairy 

 citrus groves at least, there would be no food for them. This problem 

 seems to be solved by the hibernation of the insect, which bridges very 

 nicely the period referred to. On the other hand, it is shown that 

 where conditions are favorable — that is, in sunny situations and where 

 the food supply exists due to the same conditions, activity continues 

 throughout the winter. There seems to be no possible reason for 

 doubting, therefore, the full establishment of this insect in southern 

 California and its present and prospective great usefulness. 



Scutellista cyanea, of which such good showing is now made, as 

 pointed out by Doctor Howard, is probably of Oriental origin, having 

 first been described by Motschulsky, from Ceylon, from which place 



