B< ONOMIC WORK AGAINST HOWABD SCALE. 89 



The female scale is circular and flat, about 1.5 millimeters in diam- 

 eter or about the size of a pin head. It is pale grayish in color when 

 matured, much lighter in hue than the partially matured or ever the 

 full-grown female of the San Jose scale. The scale exuvium in color 



is a dull orange when the secretion over it has been rubbed away, 

 which is quite easily done. The female inseci is broadly pyriform in 

 shape. It belongs to that class of the genus Aspidiotus where the 

 scales of the females are nearly circular, while those of the male arc 



more elongate or nearly oval, though an examination of the female 

 insect beneath the higher power lens is necessary to observe the 

 typical second pair of large lobes at the caudal end of the female, 

 which distinguishes it from that of the San Jose, Putnam, or other 

 scales of it- group. Its nature of attack and general appearance 

 upon heavily infested trees are quite enough to enable ready recogni- 

 tion from others of these types. The pallidness of the female scale is 

 quite characteristic, some individual- being nearly white. 



At the beginning of my experiment with insecticides for the con- 

 trol of the pest, very little was known with certainty of the insect's 

 exact life history. Observations, somewhat fragmentary, were, how- 

 ever, carried along through the season and some of the facts learned. 



The first observations the past spring were begun upon March 1 ( .». 

 at which time some female- were found well grown and of pale gray 

 color. Others among the>e were smaller in size, some circular and 

 some oval in outline. All these smaller-sized scales at the date men- 

 tioned showed a whitish area in their center surrounded by an area 

 much darker and in certain ca>es of a dusky gray. In the center of 

 the white area, which occupied about one-third of the surface of the 

 scale covering, a small whitish nipple was seen surrounded by a 

 rather shallow or indistinct ring or furrow. On account of the 

 weathering of these scales most of them showed reddish or orange- 

 colored centers. Out of a large number of scale- counted, about 31 

 per cent were found to contain no living insect, representing the 

 average rate of mortality from natural can--. Some of the dead 

 scale- were the result of parasitism by insects which were observed 

 later in the season, while others were dead from exposure to the 

 winter climate. 



The oval male scale 1 is much darker in color than the female. These 

 oval male scales were found to yield adult- a- early a- April 30, at 

 which time several winged specimens were seen in process of fertiliz- 

 ing the matured scales which had lived through the winter. The 

 males are of very minute size, pale brown in color, with black eye-. 

 Early in June many young scales were beginning to appear, crawling 

 over the surface of the bark in much the same active manner a- the 

 young of the San Jo>e scale. By June 9 many had settled down, and 



