Report of State Board of Horticulture. 85 



although their presence is not proof of the presence of the 

 scale, it is evidence that the vitality of the tree has been 

 seriously impaired by some cause, and in regions where San 

 Jose scale is prevalent that cause, in a vast majority of in- 

 stances, is the scale. 



DEVELOPMENT OF SAN JOSE SCALE. 



On the approach of winter scales of various ages and sizes 

 jTiay be found upon infested trees. A very large proportion 

 especially of the immature scales usually perishes during the 

 winter, but at the present writing, March 10, practically all 

 are alive. We may expect, therefore, with normal conditions 

 for the remainder of the season, to witness a very decided 

 increase in scale infestation during the coming summer. 



Fig. 1 shows a mature female surrounded by numerous 

 lialf-grown individuals. The male scales are not circular but 

 somewhat elongate. If one removes one of the large circular 

 scales the little yellow object thereby revealed is a mature 

 female. Under a moderate power of the microscope she 

 proves to be a nearly circular, yellow, sack-like body with 

 Jong slender bristle-like mouth parts. (See Fig. 3.) An 

 examination of the male shows him to be more elongate and 

 to possess the rudiments of legs, wings, eyes, antennae, etc. 

 (See Fig. 4.) The females live and die beneath their scales — 

 never leaving them; but in April the males molt for the last 

 time and soon thereafter emerge from under their scales as 

 minute, active creatures with fully developed wings. (See 

 Fig. 5.) After mating, the males die. 



In May, possibly earlier under favorable conditions, the 

 f em.ales begin to give birth to living young and may continue 

 to produce for six weeks or longer. The young are minute, 

 light orange-yellow, active creatures with eyes, bristle-like 

 Tnouth parts, two antennea or feelers, and six legs. (Ses 

 Fig. 6.) After emerging from under the protecting scale of 

 the parent each wanders over the surface of bark, leaf or 

 fruit until a suitable situation is found, when the legs and 

 antennae are folded beneath the body, the bristle-like beak 

 is slowly worked through the outer bark into the living tissues 

 beneath, from which it draws its sustenance. At any time 



