THE GENUS ACRONYCTA AND ITS ALLIES. 251 



completely as alni has. When ready to pupate, the larva will 

 bore into rotten wood, or go into a stem of reed or elder, or 

 will, like /J-/ and tridens, form a cocoon on or under the surface 

 in sawdust or loose rubbish. In rotten wood, which seems to 

 please it best, it prefers, like alni, to go in horizontally in a 

 perpendicular face, and then bore upwards ; but it differs 

 altogether from alni, in that when it has closed the opening, 

 to appearance in much the same way, the diaphragm so made 

 is the actual top (or outlet) of the cocoon proper, there being 

 no inner structure. The space excavated measures 14 mm. by 

 5 mm., and is lined with a little silk, and here and there by a 

 few chips removed apparently in giving a proper shape to the 

 cavity. The thin silk operculum coated with chips, which forms 

 the outlet of the cocoon, often shows no indication of the exit 

 of the moth. The sides of the opening made, which is an 

 irregular slit, falling together again. 



The pupa (PI. III., fig. 3) is 13 mm. in length, wings 8, 

 abdomen 5, width little over 3 mm. Pale greenish-brown, 

 with a darker dorsal line, the leg and wing cases so trans- 

 parent that the incisions of the segments within are very 

 distinct, and the tracheal vessels running down the antennae, 

 legs, etc., are obvious. The whole pupa looks extremely 

 delicate and fragile. The outlines of the fat masses are 

 visible through the abdominal walls. The spiracles are dark 

 raised rings, and are the only solid looking parts of the 

 pupa, there are two bristles in front between the eyes, the pair 

 at the bases of the antennae are also distinct ; the sculpturing is 

 extremely fine, and only distinct along the anterior margins of 

 the abdominal segments as very minute close pitting. The 

 anal armature consists of two dorsal and six ventral spines. 

 These are long compared with the size of the pupa. The 

 ventral set are regularly disposed at equal distances, the outer 

 ones set at an angle of 45^ ; all are hooked downwards. The 

 amount of corrugated base is very small, but from the spreading 

 of the spines they get well entangled with the silk of the 

 cocoon, at the base of the spines there is a sloping area of 

 longitudinal wrinkles, beneath there is a transverse ridge at the 

 base of the spines bounding some fine radiating ridges. The 

 hooks at end of the spines form more than a semi-circle. 



{To be continued.) 



