1911 ENTOMOLOGICAL SOCIETY. 6? 



in contact with unaffected trees and thus cause the free plants to become infested. 

 The spread from one province or country to another is due almost entirely to the 

 interchange of plants by nurserymen and florists. There is always the possibility 

 of introducing scale wherever a shipment of shrubs or trees is made from one place 

 to another. If the trees can adapt themselves to the new environment and become 

 thrifty under the new condition, there is hardly any question about the scale sur- 

 viving. ' In nearly all cases the scale undergoes the change without any apparent 

 inconvenience. 



Nature of the Injuries. 



As nearly all scales derive their nourishment from the juices of the plant it 

 is evident that a considerable weakening in its vitality must result. When only a 

 few insects are present as we found on trees attacked by our native species, there 

 Beems to be very little injury to the tree, but when swarms of these occur in the case 

 of the imported species the health of the tree is so impaired that in some cases death 

 occurs. In cases where the trees do not actually die, but are rendered weak, a cor- 

 responding weakening is shown in the quality and quantity of the fruit. Some of 

 the characteristics of the injury are seen in discolorations of the leaves and tissues, 

 malformed and discolored fruit, and to some extent early maturing and falling 

 of the leaves. 



Life-History. 



Most of the Homoptera have incomplete metamorphosis, but in the Coccidae 

 only the females have incomplete metamorphosis; the males pass through the four 

 stages. The eggs are seldom laid in exposed situations as is the case in their allies, 

 the Aphids and Aleyrodids, but various means are provided for their protection 

 from predaceous animals and from the weather. The Cottony Maple Scale lay 

 their eggs in. sacks formed of a cottony-like substance, which surrounds them. 

 Others, such as Physohermes dbietis, are deposited in a very peculiar pouch-like 

 organ formed by the folding in of the outer epidermis. In Orthezia the female 

 carries the eggs between the long waxen plates at the posterior extremity of the 

 body. The most common color of the egg is yellow or pink, but a few are crimson, 

 such as that of Chionaspis solids and in some species of Paralatoria they are dark 

 mauve. The number of eggs laid by an individual varies from 25 to two or three 

 hundred. 



The larvae, upon hatching, in the majority of species, remain for a few days 

 within the covering provided for them. Soon they leave this house and become 

 quite active, seeking the new and tender tissues, where in most cases they settle 

 down and immediately insert their long sucking apparatus into the tissues, and in 

 the case of the female, remain stationary until death. 



The pupal stage occurs only in the males. After a few days of active larval 

 life they withdraw their tubes and undergo marked changes characteristic only of 

 the Coccidae. 



Most of the adult males being destitute of mouth parts live only a few hours, 

 or at most a few days. 



The female adult is characterized by the absence of wings and by its well de- 

 veloped mouth parts. They are usually flat and pyriform in shape and covered 

 with scales made from the secretions of their bodies. There are sometimes one and 

 sometimes several ofenerations in a season. 



