8 The European Elm Scale 



of larvae and pupae are ejected and through which the mature insect 

 escapes. Newly excreted male cocoons are pure white in color and re- 

 semble tiny grains of rice. "When clustered about the bases of small 

 twigs or when occurring in patches on smooth bark or in long rows 

 between the projecting ridges of cork on cork elms, they are decidedly 

 conspicuous; on badly infested trees, patches on the bark. of some 

 limbs are fairly white with them, Plate V. 



FIRST PDPA 



Length, 1.11 mm. to 1.38 mm. Breadth, .54 mm. to .63 mm. Out- 

 line ovate, narrower toward head. Thoracic region narrower than the 

 abdominal, whose lateral margins curve bluntly to an obtuse three- 

 lobed apex with lobes of about the same shape, the central one broad- 

 est. Division into head, thorax, and abdomen obscure. The wing- 

 pads are fleshy sacs of about equal length and breadtfi, turned under 

 obliquely on the ventral surface. The legs and antennae are short, 

 elongate sacs without distinct segmentation. Plate VII. 



SECOND PUPA 



Length, 1.11 mm. to 1.38 mm. Breadth of abdomen, .48 mm. to 

 .60 mm. Breadth of thorax, .45 mm. to .51 mm. Outline elliptical. 

 Thoracic region slightly narrower than the abdominal, which tapers 



Reno, Nevada, March 11, 1907. 

 *Among three thousand larvae, eighteen had excreted more or less 

 complete cocoons; eleven of which contained living larvae almost com- 

 pletely denuded of their usual dorsal covering of waxen bristles. Six cocoons 

 were incomplete, the larvae within them were distended and dark, the seg- 

 ments showing distinctly. The cocoon consists of filaments of wax which 

 are excreted in abundance from both the dorsal and ventral surfaces. On 

 the bark there were several larvae whose backs were covered with curving 

 filaments of wax, the beginnings of cocoons, Plate "V. 



April 9th, 1907. 

 Male cocoons are now abundant. Some occur in cracks in the bark; 

 others are concealed in and around the semi-cocoons of dead females. 

 Clusters may be seen here and there on the bark; in one instance I counted 

 one hundred on less than one square inch of space. In fifty cocoons from 

 various situations on the bark, there were no mature males and none of 

 the cocoons were empty. Pupae are not numerous as yet; about one in 

 each dozen cocoons. 



April 15, 1907. 

 On cocoons kept in the laboratory for a few days, cast larval and pupal 

 skins are found adhering loosely to the posterior end out of which they 

 were ejected by insect. These cast skins are yellowish or cream colored; the 

 larval skin is easily distinguished from the pupal integuments by its long 

 proboscis. Male cocoons formed in the laboratory are pure white, those 

 excreted out of doors soon become dirty-grey from accumulated dust. 



