28 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 61. 



cocoon is generally in sand or earth, but occasionally in the cotton 

 of the ament. with particles of sand or ament cotton adhering to it. 



Pupa. — 5.5 mm. long. Head: 1.25 mm. wide; dorsal epicranium 

 to and including eyes, black ; ventrally pale, including antennae and 

 area basad ; tips of mandibles brown. Body : The tergum darfened 

 (nearly black) but paling somewhat posteriorly with the ultimate 

 segment yellowish ; the venter yellowish ; and the legs and wings white. 



Host. — Salix humUis Marshall. 



Be?7iarks.— Described from material collected April 21-23, 1915, 

 at Falls Church, Virginia, by C. P. Heinrich supplemented by rear- 

 ing notes from several other collections and some field observations. 

 These larvae work in the pistillate aments of willow, causing a prema- 

 ture issuance of " cotton ". The work was first observed April 18, 



1913, and in the latter part of the month, April 23, 1913, the pre- 

 pupae began to leave the aments and seek the ground for places to 

 spin cocoons. The prepupae became pupae about the first of April, 



1914, and issued as adults from about April 10-20. It is probable 

 that these individuals were retarded considerably in that they were 

 reared in cages under somewhat unnatural conditions and that these 

 events occur about 15 days earlier in nature. 



Family PTERYGOPHORIDAE. 



Subfamily Acordulecerinae. 



Genus ACORDULECERA Say. 



The larvae described in the following pages differ considerably 

 from those on the preceding pages. They can be readily distin- 

 guished by their antenna which consists of four circular disks not 

 concentric but arranged to form a diamond or square (fig. 8^) and 

 the presence on the postepipleurite in certain abdominal segments 

 (in the following on urites 2^ and 8 and urites 2-5 and 8) of a 

 prominent cresent-shaped area (fig. 8*). 



The following table separates the species described below: 



1. Crescent-shaped area on urites 2 to 5 and S manra. 



Crescent-shaped area on urites 2 to 4 and 8 2. 



2. Uropods on urites 2 to 7 about same size 3. 



Uropods on urites 6 and 7 distinctly smaller than those on urites 2 to 5. 



hicoriae. 



3. Head and apical leg joints brown or yellow brown nigritarsis. 



Head greenish white with dorsal brown spots; legs white except claw. 



foveata. 

 ACORDULECERA FOVEATA Rohwer. 



Larva. — Stage VI ( ? ) . 



Structure. — Head: Face view, circular in outline, oval in outline 

 viewed from side ; labrum with 4 spines ; epicranium and f rons with 



