ECONOMIC WORK AGAINST HOWAED 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 liahter in hue than the partially matured or even 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 insect is broadly pyriform in 

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

 scales of the females are nearl}^ circular, wliile those of the male are 

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

 insect beneatli 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 its 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 individuals being nearly white. 



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

 trol of the pest, very little was known with certaint}^ 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 19, 

 at Avhich time some*females were found well grown and of pale gray 

 color. Others among these 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 b}' an area 

 much darker and in certain cases of a dusky gruj. 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 scales counted, about 31 

 l^er cent were found to contain no living insect, representing the 

 average rate of mortality from natural causes. Some of the dead 

 scales 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 is much darker in color than the female. These 

 oval male scales were found to yield adults as early as April 30, at 

 which time several winged si)ecimens 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 eyes. 

 Early in June many young scales were beginning to apj^ear, crawling 

 over the surface of the bark in much the same active numner as the 

 young of the San Jose scale. By June 9 many had settled down, and 



