166 



Insect Pests. 



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

 on apple, pear, plum, clieny, 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 aliroad such food plants as butter-nuts, Stillingia sebifera, 

 Ailantbus glundulosus, Ceanothus americanus, Sassafras officinale, 

 J->sculus glal)ra, Syringa persica, Cj'sticus, etc. 



Tliis insect is found in nearly all countries where apples and 

 pears are grown. It is ^-ery abundant in Xorth America, in Africa, 



[.1. r. I). jiifii<u,i. 



FIG. 13S.— THE 3IUSSEL SCALE (LeitiJompllcS ulini ...N AITIE TWIG. 



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

 of nursery stock, and in many of our colonii'S, etc., its importation 

 is iTow guarded against by legisLation (2). 



Xormal bark gland markings must not 1)0 mistaken for Scale 

 Insects (Fig. 141) (5). 



LiFE-HiSTOiiY, Habits axd S-rnrcTUUE. 

 Ti) find this scale insect we sliould go in an old orchard, and 

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



