Vid'2 Illinois State Laboratory of Natural History. 



three pairs of well-developed and conspicuous lobes. The 

 median pair are rounded, and unusually notched on the 

 lateral margin near the tip; the second and third pairs 

 are rather flat and broad, more or less notched on their 

 margius. There are two plates between the second and 

 third lobes, one of which is conspicuous and usually 

 forked at the tip, while the other is short, simple, and 

 sometimes inconspicuous. There is also a third plate, 

 usually forked, just laterad of the third lobe. The spines 

 are prominent and about as long as the plates. The 

 first pair are situated near the lateral margin of the 

 base of the first lobes; the second, about the middle of 

 the base of the second lobes; the third, just laterad of 

 the base of the third lobe. 



Found on white elm, Ulmus am&ricana, throughout Illi- 

 nois, by the writer, and in Minnesota, on the same spe- 

 cies, by Mr. R. H. Pettit. 



Types in collections of the Illinois State Laboratory of 

 Natural History and of the United States National 

 Museum, and in the author's collection. 



This species is very common throughout the State 

 and has caused considerable damage to elms planted 

 for shade in some of our larger cities. I have also 

 found it abundant upon virgin timber, but only upon 

 the elm. I believe it to be a native American in- 

 sect, and propose for it the above-mentioned scientific 

 name, and popularly term it the "American elm scale." 

 From the character and nature of its attack it is clearly 

 a dangerous species. It is two-brooded in central Illi- 

 nois, the first brood appearing about May 1, and the 

 second about July 1. It hibernates in the egg state. 

 The average number of eggs under each scale is about 

 one hundred and five. The female attacks the trunk 

 and the branches; but the male is most abundant upon 

 the trunk and leaves, although often found upon the 

 branclies. According to one season's observations, the 

 peculiar pseudimaginal form of the male is very much 



