166 



Insect Pests. 



different kinds of trees. We find the Mussel Scale, for instance, 

 on apple, pear, plum, cherry, currant, nectarine and peach, on elm, 

 willow, birch, ash, oak, lime, poplar, cornus, roses, hazel, cob and 

 filbert nuts, and now and then on gooseberries. Fernald (1) gives 

 also for abroad such food plants as butter-nuts, Stillingia sebifera, 

 Ailanthus glandulosus, Ceanothus americanus, Sassafras officinale, 

 iEsculus glabra, Syringa persica, Cysticus, etc. 



This insect is found in nearly all countries where apples and 

 pears are grown. It is very abundant in North America, in Africa, 



[A. V. D. Rintoul. 

 FIG. 138.— THE MUSSEL SCALE {Lepklosaphes ulmij ON APPLE TWIG. 



in Australia, and New Zealand. It has been distributed by means 

 of nursery stock, and in many of our colonies, etc., its importation 

 is now guarded against by legislation (2). 



Normal bark gland markings must not be mistaken for Scale 

 Insects (Fig. 141) (5). 



LiFE-HiSTOEY, Habits and Steuctuke. 

 To find this scale insect we should go to an old orchard, and 

 examine the trunks of the trees, when a casual search will soon 



