NO.2107. DRAOONFLIES, WASHINGTON AND OREGON— KENNEDY. 309 



As in females of perparva, the late or adult black pattern is super- 

 imposed on the black pattern of the teneral and is not a development 

 from the first black pattern. This is especially noticeable in the 

 thorax, where the dorsal and humeral stripes remain sharply defined, 

 though onl}^ faintly visible until the intervening blue mesepisternal 

 stripes become almost black. 



The nymphs of both cervula and perparva are to be found in large 

 numbers in the trash among cattails in the ''tule" swamps south of 

 Sunnyside, While a rake brings out both species, the nymphs of 

 perparva are usually covered with mud, while cervula nymphs are 

 clean, though one species is about as hairy as the other. This fact, 

 in connection with that of the shorter legs of the perparva nymphs, 

 suggests that the perparva nymphs are more mud-loving and that 

 the cervula nymphs prefer the trash and aquatic vegetation above 

 the slimy bottom. 



The descriptions of the nymphs of cervula and perparva are based 

 on 10 cervula and 12 perparva nymphs which were reared at Sunny- 

 side during June and July, 1913. It is easy to notice certain differ- 

 ences in color and length of legs between the two series of exuviae, 

 when laid in two rows for comparison, but the difi'erences are so slight 

 and so easily confused by other varying conditions that I can not 

 certainly separate from a mixed series any but the most brightly colored 

 cervula larvae. Perparva nymphs may be pale brown, black, or bright 

 green, probably depending on food and nearness to molt. Usually 

 cervula nymphs are easily distinguished by their brilliant black color 

 pattern, especially the vivid banding on the legs. In some reared 

 specimens, however, the exuviae are almost without color, although 

 even in these the bands of the legs, though pale, are sharply defined. 



Nymph (figs. 120, 121, 127-132).— Length, 11-12 mm., gills, 6 extra ; 

 abdomen, 8; hind femur, 3. 



Color usually black because of the heavy color pattern, though it 

 may be very light. Among the exuviae are 7 males, which vary from 

 almost colorless to very black. 



Head with the distance between antennae relatively wide, in meas- 

 ured specimens being five-sixteenths of width of head. This extra 

 width is correlated with a greater width of the anterior edge of the 

 submentum than is found in perparva. The mentum is usually 

 slightly shorter than in perparva, thus accentuating the slightly 

 greater width. However, perhaps from warping, the mental propor- 

 tions in exuviae are not constant. Mental setae usually four in each 

 row — in one specimen five in each row. Each lateral lobe with five 

 raptorial setae, a large movable hook, and five end teeth the inner one 

 of which is large and set off from the row of four small ones by a 

 deep notch. 



