THE CANADIAN ENTOMOLOGIST. 295 



out. There is no change in the colour or pattern, except that the medio- 

 dorsal h'ne becomes somewhat more prominent, and the spiracular line 

 appears to cross the incisures. Length a day or two after the fourth 

 moult, 14 mm. 



Final Stage.— i^\di\.t g, figs. 2 and 3, mature larva x 3.) Not 

 differing from preceding stage, the general effect of the stripes being a 

 striking example of protective coloration, alternate lines of white and pale 

 green on a dark green background being well calculated to render the 

 larva inconspicuous as it rests among the clustered pine-needles. During 

 the last two instars the latero-dorsal white stripes become tinged with 

 yellow, which may deepen to a decided orange. Unlike the congeneric 

 caterpillars, the markings do not disappear as the time for pupation 

 approaches. Length when feeding has stopped, 17 to 20 mm. Duration 

 of fourth and fifth stages together, 10 to 18 days, at least two days being 

 spent upon the final mat. 



Length of Lai val Life. — The shortest span from egg to chrysalis was 

 27 days ID hours; the longest, 38 days ; the average for 12 larvje, 30 days. 



Pupation. — The caterpillais seek the ground as the time for pupation 

 approaches, and turn to chrysalids among the leaves. 



The CJirysalis. — (Plate 9, fig. 4, dorsal aspect; fig. 5, lateral aspect 

 X 8.) I am unable to find any^haracter which will serve to distinguish 

 the chrysalis oi niphon from that of i^-iis or augustus. As a rule, it is very 

 dark above, the wing-cases somewhat ruddier, the whole surface heavily 

 sprinkled with black spots and irregular blotches, variable in size and 

 arrangement, and affording no clue to the species of the enclosed insect. 

 The "slender dorsal ridge" is a variable quantity sometimes present, but 

 more often not. 



TENTHREDINID^ OF COLORADO. 



BY GEO. P. WELDON, COLLEGE PARK, MD. 



Unlike most families of the Hymenoptera, the Tenlhredinidae are not 

 highly specialized insects. They do not live in well-organized societies 

 as do many of the bees, ants and wasps, but are solitary in their habits. 

 In the case of the social Hymenoptera. we have a colony organization 

 where different kinds of individuals are entrusted with different duties to 

 perform. Such a high degree of specialization is manifest, that we observe 

 with amazement and wonder the instinctive qualities displayed by them. 

 Not so in the case of the Saw-flies: the only obligation resting upon these 



September, 1907 



