APPENDIX. 



363 



FOOD PLANTS. 



Practically all deciduous fruit trees are subject to the attacks of this 

 insect, including also various small fruits, such as the currant, gooseberry, 

 etc. It has also been found on a great many shade trees and ornamental 

 shrubs. The pear, peach, plum, apple, and cherry are almost equally liable 

 to injury. The quince is apparently more rarely troubled. Notwithstanding 

 its wide range of food plants, certain varieties of pear, strangely enough, 

 seem to be almost never attacked, if not entirely exempt. This holds, also, 

 to a less extent, with the different varieties of other fruits. Professor 

 Smith says of plums that apparently Japanese varieties ai'e favorities, while 

 those of American and European origin suffer much less. The notable 

 exceptions are, however, found in the case of pears. This is strikingly 

 exhibited with the Leconte and Kiefter varieties, which are almost exempt.*" 

 A notable instance of the latter is the case of a tree which bore both Lawson 

 and Kieffer grafts. The Lawson branch, leaves, and fruit was entirely 

 covered, while the Kieffer portion was entirely free from the scale. No 

 other variety of pear has been found equal to the Leconte and Kieffer in 

 immunity. The following list of food plants is substantially as compiled by 

 Doctor Lintner : 



THliacerv : 



Ijinden. 

 Celaslracea; : 



Euoiiynius. 

 Roxacece : 



Almond. 



Peach. 



Apricot. 



Plum. 



Cherry. 



Spirtea. 



Raspberry. 



Rose. 



Hawthorn. 



(lotonea.ster. 



Pear. 



Apple. 



Qnince. 



PMowerins quince. 

 >Snxi/rac/acear : 



Gooseberry. 



Currant. 



Flowering currant. 

 Ebenacece : 



Persimmon. 

 Leguminoitece : 



Acacia. 



Urtieacea; : 



Kim. 



Osage orange. 

 JiKjld n dacecn : 



English walnut. 



I'eean. 

 Betukicew : 



Alder ? 

 Salicucew : 



Weeping willow. 



Laurel-leaved willo' 

 (from Asia.) 



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 passed under the pro- 

 tection 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 the most careful observation by Mr. Pergande on 

 potted plants in the insectary, and its history, which has hitherto been very 

 imperfectly worked out, has been thoroughly and carefully elaborated. 



The winter is passed by the nearly full-grown insects under the protection 

 of the scale. Early in April in this latitude the hibernating- males emerge, 

 and by the middle of May the overwintered females mature and begin to 

 give birth to a new generation, continuing to produce young for a period of 

 upward, of six weeks, when they reach the limit of protection of young and 

 perish. 



*Mr. Charle.s Parry has recently observed cases in which both KietTer and Leconte 

 pears have been badly damaged. 



