LIFE HISTORY. 43 



The second undoubted record is of material sent to Doctor Howard 

 for determination by Dr. James Fletcher, entomologist of the Canadian 

 Central Experimental Farm at Ottawa, who reported that the infested 

 oranges sent had been forwarded to him from British Columbia and had 

 been imported from Japan. These oranges, evidenth^ of a mandarin or 

 tangerine t3^pe, showed undoubted infestation with the San Jose scale. 

 Jt is therefore evident that this scale insect may occasionally infest 

 the orange, but the long coexistence of the San Jose scale and orange 

 culture in southern California ^ould seem to indicate the practical 

 immunity of the orange tree from this scale pest. An earlier record 

 of the San Jose scale on a citrus plant, by Mr. Cockerell, has always 

 been under the question of a misidentihcation of the food plant. 



LIFE HISTORY. 



In common with all the armored scales, the life round of this insect, 

 with the exception of a few hours of active larval existence and an 

 equally brief winged existence in the case of the mature male, is past 

 under the protection of a waxy scale. This scale covering conceals 

 the real insect beneath and prevents any easy observation or study of 

 its life history. The San Jose scale has been under most careful 

 observation b}^ Mr. Pergande on potted plants in the insectary, and its 

 historj^, which has hitherto been very imperfectly worked out, has been 

 thoroh^ and carefully elaborated. 



The winter is past by the insects in a half-grown condition under 

 small black protecting scales, mere points, just visible to the naked 

 eye. The male scales arje normalh^ vastly in excess of the females, 

 often representing 95 or more per cent. Early in April, in this lati- 

 tude, the males transform to pupae and emerge, and this gives the 

 appearance of a sudden death of the great majority of these overwin- 

 tered insects on the bark, and has led to some confusion in interpret- 

 ing the effect of washes. The females at this period have arrived 

 at the stage of impregnation, and the delicate two-winged males dis- 

 appear after a few days. About a month later, varying with the cli- 

 mate, the overwintered females come to full maturit}^ and begin to 

 give birth to a new generation, continuing to produce 3^oung for a 

 period of upward of six weeks, when they reach the limit of produc- 

 tion of young and perish. 



The adult female gives birth immediately to living 3^oung, differing 

 in this respect from most other scale insects. Ordinarily eggs are 

 deposited beneath the scale, which in the course of a longer or shorter 

 time hatch, and the j^oung larvae make their escape and migrate to 

 different parts of the plant. In the case of some scale insects the 

 female fills its scale with eggs in the fall and perishes, the eggs win- 

 tering over and hatching the following spring. In others the insect 



