22 



outer ends of the breathing folds in Aleyrodes citri (viz.. one on each 

 side of the body opposite the first pair of spiracles and a single one 

 at the anal end) the wax tubes are noticeably smaller than usual, and 

 the ribbons secreted there are narrower than elsewhere. The dorsal 

 wax secretion consists of a double submarginal series of glassy waxen 

 rods and a more dorsal series of from five to eighteen (typically 

 eight) rods. There seems to be no distinction between these rods 

 except in size and position of origin. The outer series consists of 

 from about fifty to seventy-five (fifty-seven to seventy-two being the 

 limits actually observed) rods, fairly constant in size, in full grown 

 pupae being almost invariably less than one-fifth the width of the 

 body in length. They are rather more blunt at the tips than the 

 other rods, proportionally narrower, and usually curve downward 

 over the margin. The series which I designate the inner sub- 

 marginal series is distinguished from the outer series by the much 

 larger size of the rods. There are typically ten or twelve (five or 

 six pairs) in this series, but may be as few as five. They usually 

 arise a little mesad to the rods of the outer series, and with the ex- 

 ception of the most anterior pajr appear never to arise farther away 

 from the outer series than the width of their bases. The anterior 

 pair is almost invariably within twice the diameter of their base from 

 the outer series. Typically, the inner series of rods consists of three 

 on each side in front of the mesothorax ; one on each side near the 

 base of the abdomen ; one on each side nearly opposite the vasiform 

 orifice, and one on each side of the groove mentioned above which 

 connects the apex of the vasiform orifice with the caudal margin of 

 the body. In full grown pupae the rods of the inner series are from 

 five to ten times as long as those of the outer series. They are 

 usually directed upward and curved inward over the dorsum. The 

 rods of the dorsal series, typically eight incumber, are of about the 

 same size as those of the inner sub-marginal series, and arise as fol- 

 lows : The first pair on the cephalic region, one on each side about 

 one-fourth the distance from the cephalic margin of the body to the 

 base of the abdomen ; the second pair, one on each side, about half 

 way from the cephalic margin of the body to the base of the abdo- 

 men ; the third and fourth pairs on the sides of the third and fourth 

 abdominal segments respectively. The dorsal rods are subject to a 

 great deal of variation (Plate VI, Figs. 28-30), the most frequent be- 



