36. Several young scales in the blacK 

 stage. (Much enlarged) 



37. Adult female scales and young 

 scales in the white stage. (Enlarged) 



38. Male scale and young scales in 

 the white stage. (Enlarged) 



39. Adult female scale. (Greatly 

 enlarged) 



How to Kill the San Jose Scale— By e. p. Felt 



State Entomologist 

 ol New York 



IS THE SAN JOSE SCALE IN YOUR NEIGHBORHOOD ?— IF SO, YOU WANT TO DO SOME- 

 THING ABOUT IT AT ONCE ! — THE GREATEST INSECT PEST OF MODERN TIMES 



THE San Jose scale (pronounced Hozay) 

 is widely distributed in America, and 

 especially in the vicinity of some of our larger 

 cities, particularly New York. Its destruc- 

 tive powers are greatly increased by its small 

 size and obscure color, which combine to 

 render it extremely inconspicuous, and por- 

 tions of trees are frequently covered by the 

 pest or limbs killed before the owner is 

 aware of any trouble. 



This species may be distinguished from all 

 others by the form of the female scale, it 

 being grayish or yellowish gray, about one- 

 sixteenth of an inch in diameter, and with 

 a yellowish central elevation representing 

 a cast skin. There are several allied, nearly 

 circular scales, with the elevation or nipple a 

 little to one side of the centre, which some- 

 what resemble this species, but fortunately 

 these very rarely occur in sufficient numbers 

 to cause appreciable damage. Young San 

 Jose scales are dark gray, sometimes almost 

 black, with a distinct central nipple bounded 

 by a grayish ring. Both adult and young 

 when located upon green twigs, leaves or 

 fruit produce a very characteristic purplish 



40. Spraying & Japanese quince with a little broom 



discoloration in their immediate vicinity, 

 and for this reason the pest is easily recog- 

 nized in mid-summer upon foliage and fruit, 

 since it has a marked tendency to establish 

 itself upon the latter, particularly apple and 

 pear. This characteristic stain also occurs 

 in underlying green tissues, and may be 

 exposed by cutting the infested bark. Any 

 abnormal, rough, scurfy appearance upon 

 twig or branch should arouse suspicion. 

 Sometimes this is due to abnormally devel- 

 oped or peculiar lenticels, and occasionally 

 fungi produce very much the same general 

 appearance as a bad infestation of San Jose 

 scale. If living scale insects are present, the 

 drawing of an inclined knife-blade or even 

 one's thumb-nail over the surface will cause 

 the exudation of a yellowish fluid from the 

 crushed bodies of the underlying insects. 

 There are two native species which are fre- 

 quently confused with the San Jose scale, 

 though both are very different. One, the 

 apple-bark louse, has a brown, elongated, 

 slender, pear-shaped, usually slightly curved 

 scale about one-eighth of an inch in length. 

 This species occurs upon many trees and 

 shrubs, and winters in the egg. The other, 

 the scurfy bark louse, has an irregular white 

 or dirty white scale about one-tenth of an 

 inch in length, which expands irregularly 

 from a slender, yellowish tip. This, like the 

 apple-bark louse, winters in the egg and 

 occasionally forms a thick, dirty white in- 

 crustation. 



An understanding of the life-history of 

 this insect is essential to its intelligent con- 

 trol, otherwise our efforts may be sadly mis- 

 directed. The winter is passed by this in- 

 sect in a half-grown condition. The over- 

 wintering scales are small, black, circular 

 objects with a central nipple and one or two 

 grayish rings. Vital activities are nearly 

 suspended during the winter, being re- 

 sumed with the approach of warm weather, 

 and the insect, lying beneath its sheltering 

 scale, begins once more to drain the tree of 

 its sap. This is accomplished by means 

 of a long, slender proboscis composed of 

 several thread-like setae, which are thrust 

 into the bark and serve as a tube through 

 which the pest may draw its nourishment 

 from the underlying tissues. The first out- 

 22 



ward indications of life are seen in the appear- 

 ance of the winged males, slight, reddish in- 

 sects with two membranous, almost veinless 

 wings, about the middle of June in the lati- 

 tude of New York. The minute, yellowish,, 

 crawling young, appearing for all the world 

 like animated specks, escape from under the 

 protecting shelter of the mother about this 

 time, and for a period of approximately six 

 weeks the females continue to produce 

 young, each averaging about four hundred^ 

 or from nine to ten every twenty-four hours. 

 The new-born wanders forth in search of a 

 favorable place to establish itself, and within 

 relatively few hours (on an average a little 

 over twenty-seven) settles at some convenient 

 point and works its slender, hair-like beak 

 through the bark. If it be a female, it never 

 moves from this spot, and soon loses legs, 

 antennas and eyes and becomes virtually an 

 animated pump drawing the vital fluids from 

 its host. The development of the protect- 

 ing scale begins even before the young has 

 selected its feeding-place, as very minute, 

 waxy filaments which spring from all parts 

 of the upper surface of the body, rapidly be- 

 coming thicker and slowly matting down 

 to form the circular, white scale with a de- 

 pressed ring and central elevation. These 

 insects are then in what is known as the 

 white stage, and in a few days the covering 

 scale turns to a black or dark color with one 

 or more lighter rings. The female scale 

 insect requires about thirty days to attain 

 maturity, and the male from twenty-four 

 to twenty-six; thus the round of life may be 

 completed in from thirty-three to forty days. 

 Detailed studies made at Washington show 

 that four entire generations are normally 

 developed, and that under certain conditions 

 there may be a partial fifth. The fecundity 

 of the insect, in connection with its ability 

 to produce a number of generations annu- 

 ally, results in an enormous increase, and 

 in the vicinity of Washington it is estimated 

 that a single individual under favorable 

 conditions may in one season become the 

 progenitor of over three billion. It is no 

 wonder that many trees succumb to the 

 fearful drain. The short period necessary 

 to complete the life cycle, and the extended 

 time during which each female produces 



