192 DAVENPORT ACADEMY OF SCIENCES. 



legs somewhat paler. Eyes dark brown or purple. Ocelli col- 

 orless, clear, bordered along the inner side by a broad, somewhat 

 lunate, black margin. Prothorax marked with two transverse 

 rows of three small and very pale dusky spots. Antennae slender; 

 basal joint shortest and stoutest, joint 2 somewhat longer, thin- 

 nest at base, the apex rounded and divided by five or six more 

 or less distincly scalloped or scaly annulations; joint 3 very long 

 and slender, of almost uniform thickness, rather more than five 

 times the length of the second joint, and usually slightly con- 

 stricted at about its basal fourth; sharply and quite closely annu- 

 lated, with the annulations more or less irregular; upper sensorial 

 membrane about two-fifths the length of the joint, the lower one 

 inconspicuous, small and rounded; apical nipple short, truncated 

 at tip, bearing apparently two short, knobbed hairs. Legs rather 

 long and slender. Body stout, covered with minute, obtuse tuber- 

 cles, though less dense than in the pupa. Head and prothorax 

 rugose and somewhat tuberculated, the rugosity more pronounced 

 on the head. Wings large, broad and pale dusky; stigmata and 

 venation darker; course of stigmal vein in many specimens abnor- 

 mal, not entering the stigma but curving backward a short distance 

 therefrom and connecting with the discoidal vein. This abnor- 

 mality sometimes occurs in both wings and at others either in 

 one or the other. 



The first observations regarding this gall were made May 13, 

 1883, and, as it will help to throw some light on the question of 

 the formation of this and many other galls, I will here include 

 the few notes made at the time. 



This gall, a very beautiful and curious object, I find, after a 

 careful examination, to be nothing else but an abnormally great 

 enlargement of a pore and the filaments or hairs surrounding same. 



From the position of the galls, there can be no doubt whatever 

 but that the young insect, as soon as it finds a suitable place, 

 stations itself directly over a pore on the under side of a young 

 leaf, into which it inserts its proboscis to extract the sap and to 

 remain in this position. The irritation, caused by the sucking, 

 gradually enlarges the pore so that the insect can sink into the 

 opening; the rapid growing of the leaf causes the walls of the 

 pore to prolong and the thus formed cell to widen till a regular 

 cell is formed, enclosing the insect completely. 



