ODONATA OF THE VICINITY OF GO HOME BAY 71 



SESSIONAL PAPER No. 39b 



inhabit the well aerated waters at the foot of the "Chute" and other stations 

 where the imagos occur. They transform on the rocks close to the water's edge, 

 generally early in the morning. In 1907 the first newly-emerged specimens ap- 

 peared on the Station Island on June 23rd and the last adult was taken on August 

 14th. In 1912 they were somewhat earlier, appearing at the "Chute" on June 15th. 



24. Gomphus lividus Selys. 



Syn. G. sordidus Hagen. 



This is a very abundant dragonfly, frequenting the shallower waters of the 

 bay where the aquatic vegetation is scanty and the shores more or less wave- 

 beaten. It is absent from the marshy bays and inland lakes and also from the 

 steep rocky shores where the water is of considerable depth. The nymph livea 

 in a more or less muddy or sandy bottom. 



Transformation begins at almost exactly the same time as that of G. brevis^ 

 and usually takes place before 8 o'clock in the morning. The nymphs of these 

 two species may be found together but on the whole those of G. lividus prefer 

 quieter water than those of brevis. 



In 1907 this species began to emerge on Station Island on June 22, becoming 

 abundant in two or three days. In about a fortnight, however, they were nearly 

 gone though a few females were seen as late as July 20. In 1912 the first young 

 adults were observed on June 16 and they continued to emerge for at least 10 days, 

 subsequently. By this time the species was very abundant and many pairs were 

 seen in copula. By the end of the month all were mature, and shortly afterwards 

 their numbers began to thin out, though occasional individuals were seen until 

 the end of July. The season of flight is nearly coincident with that of the may- 

 flies Ephemera simulans and Hexagenia bilineata, upon which they largely feed. 

 They also devour small moths, caddis-flies, etc. 



The flight of the adult males of this species is peculiar and is easUy distin- 

 guishable from that of the other species of Gomphus occurring about Go Home 

 Bay. It consists of a series of ascending and descending or dipping movements, 

 the insect describing a series of deep curves, with the convexities downwards. 

 These motions are not seen during the teneral state. 



G. lividus is frequently captured and eaten by Hagenius brevistylus, but by 

 the time the latter is common, lividus has already considerably diminished in 

 numbers. 



Gomphus exilis Selys. 



This is the most generally distributed Gomphine of the Go Home Region, 

 being associated with both G. lividus and G. spicatus. It is most abundant in the 

 shaflow marshy bays, but it is quite common on the Station Island, where the 

 nymphs live in the comparatively shallow water on the south-east shore, associated 

 with G. lividus, Macrornia illinoiensis, etc. 



