27 



To the above list Professor Fernald now adds Auburndale and Belcher- 

 town, while the writer has recently discovered a limited occurrence of 

 the scale in Maiden. 



As is well known, the principal method by which this insect has been 

 disseminated throughout the country is thi'ough the sale of infested 

 nurseiy stock. Without doubt local distribution is facilitated by birds 

 and insects. The young lice, although minute, are active, and, readily 

 crawling upon the feet of birds or the bodies of insects, may be trans- 

 ported to a considerable distance. In an infested orchard large num- 

 bers of the scale usually will be found under and around birds' nests ; 

 and. when examining trees for the scale, those iu which birds' nests are 

 located should receive the most critical attention. 



Desceiptiox of the Insect. 



AVhen the San Jose scale is abundant, its presence is soon betrayed by 

 its eliect upon the trees. Infested trees are usually stunted, do not put 

 forth vigorous foliage and make but little growth. An examination of 

 such sickly trees frequently results in the discovery of multitudes of the 

 minute, dark-gray, circular or slightly oval scales massed on the trunk 

 and older branches, while the younger growth is thickly dotted with 

 single scales. The scales are often so numerous on the trunk as to 

 make a thick, scurfy crust, that may be removed in a laj^er. While 

 most commonly found on the bark, they also occur on the fruit and 

 leaves. The writer has found this insect abundant on the fruit of the 

 Japanese quince, and in a single orchard on apples and pears. When 

 the scales occur on the fruit or young growth, they are olten bordered 

 with a purplish margin of discolored tissue. On the bark beneath the 

 scales a similar coloring is found ; but this peculiarity is not confined 

 to the San Jose scale, since the scurfy bark louse sometimes produces 

 the same effect. This discoloration of "the bark, however, is of consider- 

 able assistance in the recognition of the San Jose scale in the field. 



The nearly mature insects winter over beneath their scales, and com- 

 plete their growth early in the spring. During a period of about six 

 weeks the females give birth to several hundred young, and at the end 

 of this time the first-born insects are mature. The young larvae, after 

 escaping from beneath the female scales, appear as a fine, yellow- 

 ish dust on the bark, and swarm over the tree in search of a suitable 

 settling place. Having become fixed, they insert their beak into the 

 bark, secrete a scale, and soon become like their parents in appearance 

 and capacity for damage. The active season of the insect is doubtless 

 shorter in Massachusetts than it is farther south Accurate information 

 on this point is lacking. On May 21, 1898, I found young larvae abun- 

 dant on a badly infested, purple-leafed prune at C ambridge. Mass ; 

 while at Auburndale, Mass., Oct. 9, 1897, a few days after a light frost, 

 infested peach trees were swarming with <he young lice. This shows 

 us that here the insect multiplies throughout a season of over four 

 months. 



By isolating female scales on small trees, Messrs. Howard and jNIarlatt 

 found the number of young borne by a single female to vary from 

 thirteen to five hundred and eighty-seven ; and, assuming four hundred 

 young to be a fair average, these gentlemen find that in the course of 

 a single summer one female might become the parent of over three 

 billion progeny. When one contemplates the remarkable rapidity 

 with which this insect multiplies, — a brood of about four hundred every 

 six weeks, — what wonder is it that in the space of two or three seasons 

 this prolific pest is able to spread over even large fruit trees? The 

 lapping over of the different generations is one of the greatest hin- 

 drances to the successful use of insecticides against this insect. With 

 many of our scale insects the young appear at known intervals of time. 



