THE CANADIAN ENTOMOLOGIST 107 



somewhat similar to 1st stage, general body colour yellowish brown, 

 dark spots on dorsal surface forming more or less longitudinal lines. 

 Thoracic tubercles more prominent, and two lateral rows of ab- 

 dominal spots becoming tubercles and dorsal spots on abdomen 

 becoming slight tubercles. Hairy condition of larvae slightly more 

 pronounced. Width of head 0.4 mm.; length of bod}' 1.7 mm. 

 Third stage: similar to second stage save that the colour, with the 

 exception of the legs, is darker, so that the dorsal surface has a 

 brownish appearance with a light, medial dorsal line on the thorax. 

 Tubercles more prominent and slightly roughened. Width of head 

 0.5 mm.; length of body 2.5 mm. Fourth stage, similar to third 

 stage, save that tubercles and colour are slightly more pronounced. 

 Width of head 0.7 mm.; length of body 3 mm. Fifth stage: body 

 elongate, tapering at posterior extremity; margins of prothorax, 

 medial dorsal line of thorax and under surface, yellowish brown. 

 Head shining black and bearing several long setae; front and ^'ertex 

 depressed; prothorax with most of dorsal surface shining, dark 

 brown, lighter medially and laterally; bearing a few setse on lateral 

 margins; mesothorax brown, lighter medially, on either side of which 

 are two shining, dark brown spots; lateral margin of dorsum has a 

 prominent, dark brown tubercle with two dark brown, shining spots 

 posterior to it and two below it; metathorax similar to mesothorax; 

 abdomen brown, a double row of dark spots on the dorsum, a 

 double row of shining, dark brown tubercles on each side with a 

 single row of dark brown spots between them; under surface of 

 abdomen with five rows of brownish spots, the three median ones 

 lighter than the others; legs shining black; anus surrounded with a 

 prominent, yellowish, fleshy, circular, sucker-like disc. Width of 

 head 0.8 mm.; length of body 5.00 mm. 



The tubercles noted on the sides of the thorax and abdomen 

 contain reversible hypodermal glands which are operated when the 

 larvae is irritated, even in the recently emerged ones. The larva of 

 Plagiodera do not respond as readily as do those of Lina scripta 

 Fab. which also bear such glands. On the latter species there is a 

 minute drop of liquid exuded which is not the case in Plagiodera 

 and the odor is much more pungent. 



The sucker-like disc at the anal end is used by the lar\ a in 

 walking. Even in the recently hatched larva this disc is well de- 



