430 JOrRNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



New Haven, Conn., July 8, 1909, by A. I. Bourne. Conn. No. 

 1-16/132. 



This species is very close indeed to populicola Thos., as that insect is 

 at present understood. A large series of the latter species shows 

 considerable variation and a more thorough study should be made of 

 bred material. The co-types of hruneri in the National Museum 

 collection consist of alate forms and apterous females. The principal 

 differences noted between these types and the average specimens of 

 populicola are, apart from the size, the antennae and the body hairs. 

 Segment IV of the alate form has no sensoria or one, whereas in the 

 same segment of populicola there are usually several. In many cases, 

 however, this segment in specimens of populicola shows only one 

 sensorium. The apterous specimens of hruneri on the Connecticut 

 slide, as well as one specimen on the type slide, show hairs which are 

 stout and notched at the tip. This character is also shown in a 

 collection taken for populicola in Minnesota. All the other material 

 of populicola which the ^vl■iter has examined shows long normal hairs. 

 This character of the hairs showing in such few specimens may possibly 

 be a specific indication but the writer retains hruneri not on the strength 

 of these hairs, but on account of a lack of material suitable for dissection 

 and study in order to fix its status. The following measurements have 

 been made from the cotypes in the National Museum collection. 



Alate Viviparous Female: Antennae as follows: Segment III, 0.416 mm. with 

 17 sensoria; IV, 0.224 mm.; V, 0.208 mm.; VI (0.128+0.16 mm.), Cornicles 0.112. 



Apterous Viviparous Female : Antennal segment III, 0.368 mm. ; IV, 0.208 mm. ; 

 V, 0.208 mm.; VI (0.112 mm. + 0.144 mm.). 



Key to the American Species of Chaitophorus 

 (Alate viviparous females) 



1. Wing veins heavily bordered with dark brown 2 



Wing veins not heavily bordered with dark brown 4 



2. Antennae with very few hairs (apterous form with thick spines) . . .quercicola (Mon.) 

 Antennae noticeably hairy 3 



3. Segment III of antennae usually with several sensoria (apterous form with 



straight spine-Uke hairs) populicola Thos. 



Segment III of antennae usually with one sensorium (apterous form with notched 

 spine-Uke hairs) hruneri Wms. 



4. Feeding upon species of maples 5 



Feeding upon species of willow and poplar 7 



5. Segment III of antennae with 16 to 24 sensoria somewhat irregularly placed- on 



the basal three quarters of the segment arnericanus Bkr. 



Segment III of antennaj with 4 to 9 sensoria in a more or less even row 6 



6. Unguis of segment VI less than three times as long as the base .... negundinis Thos. 

 Unguis of segment VI much more than three times as along as the base, often 



more than four times as long lyropicta Kess. 



7. Vertex and cro'v\'n covered with reticulate areas (dorsum of apterous form 



reticulate) 8 



