194 DRAGONFLIES OF NORTH AMERICA 
159. Somatochlora williamsoni Walker 
Walk. ’06, p. 151: Mtk. Cat. p. 183: Walk. ’25, p. 78: Garm. ’27, p. 224. 
Length 56 mm. Expanse 80 mm. Me. and Pa. to Ont. and Minn. 
This is a slender, dark colored species with a yellowish face. Anteclypeus 
and median part of postclypeus darker. Upper part of frons and vertex metallic 
blue. Labrum greenish black. Thorax dark metallic green and brown with 
violet reflections. Lateral stripes obscured; the first long and straight; the second 
ovoid. Legs black, front femora brownish beneath. Wings hyaline, sometimes 
yellowish at base. Abdomen dark brown; segment 2 with three pairs of lateral 
yellowish spots, sometimes more or less confluent; 3 with a pair of dorso- and 
of ventro-lateral yellow spots; 5 to 8 often with small lateral spots. 
Walker ’25 says: 
During the first two or three weeks of adult life it may be seen about the 
edges of woods or on openings in them, hawking at a height of 30 to 50 feet, or 
even higher, and usually keeping within an area of only a few square yards for 
long periods at a time. Sometimes half a dozen may be seen flying together in 
the same area. From the middle of June to the end of their season though still 
frequenting the woods, they are more often seen about the watercourses where 
they breed. They frequent sluggish streams, usually shady but sometimes 
open and bordered with a zone of standing aquatic plants. Here the males patrol 
the margins, flying in rapid movements, interrupted by periods of almost motion- 
less suspension in the air. In the sunlight they commonly fly two or three feet 
or more above the water, while in the dense shade they are generally only a few 
inches above the surface. Sometimes they may be seen hovering in a dark 
recess under an overhanging bank, and at such times they may be scarcely visible 
except for the brilliant green eyes. Frequently they will remain suspended in the 
air for many minutes, occasionally darting away a few yards and then returning to 
the same spot. 
160. Somatochlora incurvata Walker 
Walk. 718, p. 367: ’25, p. 142. 
Length 49-55 mm. Expanse 66-69 mm. Mich. 
Labrum black, anteclypeus yellow, postclypeus black in middle. Sides of 
frons ochraceous or brownish yellow, top of frons, vertex and occiput metallic 
blue. Thorax metallic blue or greenish. Side stripes yellow, rather short and 
wide, obscurely rounded at ends. Legs black. Wings hyaline, stigma tawny. 
Abdominal segment 2 with two pale spots above and below the auricle, some- 
times connected; 3 with short basal triangular yellow spots below and above the 
midlateral line; 5-8 with small basal yellow spots, largest on 6, minute on 8. 
Walk. ’25 reports that they 
Were taken along the shore of Lake Superior, flying low over the beach, and in 
a clearing some quarter of a mile away from the lake, in both cases flying with 
swarms of Aeshna..... They were found swarming on the beach during the 
day, when the wind was off shore, and in a clearing at the close of a warm day 
from about 5 o’clock until sundown or later. If the day were cold they would be 
entirely absent. 
