388 J llniois iState Laboratory of Natural History. 



I found this insect very abundant ou buclveye in Santa 

 Clara countj^ California, in 1892. It attacks the trunk, 

 branches, and smaller twigs, but so far as I have ob- 

 served is not found upon the leaves. It colonizes most 

 abundantly on the under side of the branches, and often 

 accumulates in masses two or three scales deep. This 

 is accounted for by the fact that many scales adhere so 

 closely to the branches that the young larvae are unable 

 to get out, and therefore attach themseh^es to the bark 

 underneath the scale. It is not an uncommon thing 

 to find a dozen or more young larvae attached in this 

 manner underneath the scale of the parent insect, and 

 as the scale is formed and the insect matures the old 

 scales are naturally pushed outward. The color of the 

 scale conforms so closely to that of the tree that it is 

 very difficult to detect the scale, except where it is 

 quite abundant. 



I have frequently bred a hymenopterous parasite, 

 Prospalta m.urtfeldti Howard, from scales of this insect. 



Aspidiotus ulmi sp. n. (Plate XXXII., Fig. 4 and 5.) 



Scale of female. — The scale of the female is circular or 

 nearly so, quite convex, with exuviae central or slightly 

 laterad of the center. Exuviae in fresh specimens bright 

 orange-yellow; but dirty whitish in old material. The 

 color of the scale is either dirty whitish or tan-colored, 

 the latter color being due to the covering of the cork- 

 like bark. There is a well-developed, snowy white ven- 

 tral scale, which usually adheres to the bark when the 

 scale is removed. The ventral scale often adheres to the 

 dorsal scale, especially when the insects are massed to- 

 gether, completely enveloping the insect. The interior 

 of the dorsal scale is also snowy white. Diameter usu- 

 ally about 1.5 mm. 



Scale of male.— The scale of the male is more or less 

 circular, sometimes elongate-oval, of the same general 

 color as the female scale. Ventral scale well developed 

 and snowy white, usually about .70 mm. long. 



