12 The Bulletin. 



lower brauclies, next to the street or walk, being most frequently infested, 

 thus indicating that the English Sparrow plays an important part in its 

 spread in such places. 



Spread hy Insects. — Insects play a part in the spread of this pest simi- 

 lar to that of the birds. Especially during the blossoming season, many 

 insects are busy going from tree to tree and are thus liable to spread the 

 young scale insects. 



Spread hy Commerce in Nursery Stock. — All the means thus far con- 

 sidered contribute to the spread of the San Jose Scale to a limited ex- 

 tent — not more than a few miles at most. But by the shipment of in- 

 fested trees from place to place the scale may be spread over great dis- 

 tances. If a nursery in California or Oregon were infested and trees 

 were ordered by a grower in North Carolina the trees would be dug and 

 shipped, with scales attached, and the infestation would begin where the 

 trees were planted. 



We have stated that the insects have a tendency to settle near the buds. 

 Now if a nurseryman desires to propagate a variety, it is done by cutting 

 the buds and placing them in a young tree. If the tree from which the 

 buds are taken be infested with scale, the nurseryman is likely to intro- 

 duce the insect into his nursery, and then send it out to his customers on 

 the trees which they purchase. 



We can see, therefore, that although the San Jose Scale has very 

 limited natural powers of spread, it is nevertheless able to spread with 

 considerable rapidity, aided, as it is, both by accidental causes and by 

 the hand of man. 



What Kind of Plants May be Infested?— The San Jose Scale is not 

 capable of living and thriving on all kinds of plants, and it is extremely 

 important that the grower should know which ones are most liable to 

 attack. It is primarily a pest of orchard trees and it is an exception, 

 rather than the rule, to find it on any other. Of the orchard fruits, 

 peaches, plums, apples, pears, and cherries seem to be worst attacked 

 and die most readily in the order named. Certain varieties, especially 

 of pears, seem to show considerable resistance, the Kieffer, Leconte, and 

 Garber seeming to be less attacked than others, though by no means 

 exempt. Sour cherries are also resistant. 



Currants, Gooseberries, Koses, Grapes, Osage-orange, Thornapple, and 

 Japan Walnut are all quite subject to the San Jose Scale, though not so 

 readily attacked as the orchard fruits. Then there comes a long list of 

 other plants upon which it is of accidental or rare occurrence, such as 

 Persimmon, Walnut, Poplar, Chestnut, Sumac, Catalpa, Willow, Linden, 

 Ash, Dogwood, Elm, Maple, Strawberry, Raspberry, Milkweed, Spruce, 

 Cedar and even Crabgrass. But it must be remembered that its occur- 

 rence on the last is unusual and as a rule they are not attacked, even 

 though they stand close to orchard trees that are badly infested. 



Forest and shade trees are not commonly infested with the San Jose 

 Scale, and are not appreciable factors in harboring or spreading infec- 



