260 MAINE AGRICULTURAL EXPERIMENT STATION. 1917. 



and split at the time of molting) ; of the dorso-lateral tubercles, the 2 

 posterior have fused into one, the upper anterior is non-setiferous, and 

 the lower anterior has fused with the lateral tubercle; the mid-ventral 

 tubercles are present and homologous with those of the abdominal seg- 

 ments; but no other homologies can be drawn. 



Prothorax. Modified dorsally into a strongly chitinized cephalic 

 shield; the mid-ventral tubercle is the only tubercle which the writer 

 can homologize with those of the abdomen. 



Spiracles. There are 9 pairs of spiracles, 8 abdominal and one tho- 

 racic; the abdominal spiracles are borne on little tubercles located just 

 above the lateral tubercles on segments 1 to 8; the thoracic spiracle is 

 borne on a tubercle just above the base of the mesothoracic leg; an homol- 

 ogous tubercle, present on the metathorax, shows no indication of a 

 spiracular opening. 



Legs. The legs are composed of 5 segments, with an anterior and 

 a posterior sclerite externally, at the base ; the anterior sclerite is setiferous 

 in the prothorax, and non-setiferous in the mesothorax and the meta- 

 thorax; the posterior sclerite is setiferous in all 3 thoracic segments; 

 the proximal segment is incompletely chitinized ectad, and almost not 

 at all entad; it fits closely into a socket formed by the infolded body 

 wall, with which it is continuous ; the second segment, which is chitinized 

 proximally, is barely visible ectad, but is much larger entad; the third 

 segment, strongly chitinized ectad, is about equal in size to the second 

 segment; the strongly chitinized fourth segment is the longest of the leg 

 segments; the short, strongly chitinized distal segment bears a single 

 pulvillus and a single inward-curved claw. The setae are the same on 

 all of the legs, except that the proximal segment of the prothoracic leg 

 lacks the anterior seta borne on the ental surface of the mesothoracic 

 and metathoracic legs. There is no homology between the segments of 

 the larval legs and those of the imago. 



Figures. The arrangement of the setae and tubercles of the full 

 grown larva is shown in the following figures : dorsal aspect, figure 18 

 A (head, thorax, abdominal segments 1, 8, and 9) ; ventral aspect, figure 

 18 B (head, thorax, abdominal segments 1, 8, 9, and 10) ; lateral aspect, 

 figure 18 C (head, thorax, abdominal segments 1, 8, 9. and 10). The 

 structure of the larval legs is shown in the following figures : ectal aspect, 

 figure 20 A ; ental aspect, figure 20 B (both drawings were made from 

 mesothoracic legs). The structure of the larval mouth parts is shown 

 in the following figures : labrum, figure 19 A ; mandible, figure 19 B ; 

 maxillae and labium, figure 19 C. A first instar larva is illustrated in 

 figure 24 ; a second instar, in figure 25 ; and a third instar, in figure 26. 



Color changes of the larva during growth. The body wall 

 of these larvae is covered with minute cuticular nodules, which 

 together with the tubercles, are the pigmented portions of the 

 body. Just after hatching or immediately after a molt, the integ- 

 ument is translucent, and the larva appears bright orange yellow, 

 as no pigment has yet been formed, and the yellow fat-body 



