BUIvIvETiN OI^ THE BUREAU OI^ FISHERIES. 



GOMPHUS VASTUS Walsh. , i 



\ 



Gomphus vastus Walsh, Proc. Acad. Nat, Sci., Phila,, 1862, p. 391. 



This species was third in abundance, judging by the number of skins obtained, and it takes an active 

 part in the odonate life around the ponds. 



While the imagoes emerge along the river bank, and while many of them remain there, others migrate 

 to the vicinity of the ponds. Most of these migrants are females, although the/e is a respectable sprin- 

 kling of males. And yet none of them ever deposits eggs in the ponds ; they all return to the river. Hence 

 the part which they play is strictly confined to the imagoes, and consists wholly in the consumption of 

 various insects and the teneral imagos of smaller dragonfiies, 



GOMPHUS EXTERNUS Hagen. 



Gomphus externus Hagen, Monogr. Gomphidae, 1857, p. 411. 



This species was second in abundance, as shown by the skins collected. The sexes seemed fairly 

 well divided, and specimens could nearly always be seen along the cinder road to the north of the 

 ponds or in the vegetation on the embankments. They are active and restless himters and voracious 

 eaters. One female was observed July 18 eating an Argia putrida imago and was so intent upon her 

 meal that she allowed an approach to within 2 feet. She chewed and swallowed every scrap of the 

 large damselfly except the wings and had no sooner finished than she caught another and ate it similarly. 

 Such gormandizing must of necessity play an important part in the ecology of the ponds. Like vastus, 

 this species returns to the river for ovipositing, and its nymphs are never found in the ponds. 



Like plagiatus, emergence takes place during the night, and many tenerals were found early in 

 the morning at the season of transformation, which seems to last through June and July. 



GOMPHUS SUBMEDIANUS Williamson. 



Gomphus submedianus Williamson, Entomol. News, 1914, vol. 25, p. 54. 



This species was found only at Patterson Lake and Stmfish Lake, on the Illinois side of the Missis- 

 sippi River, just above Fairport. The males were plentiful along the banks of the lakes, while the 

 females were found in swampy places some distance back in the woods. Specimens were sent to E. B. 

 Williamson, the founder of the species, and he very kindly confirmed their identification. The males 

 usually fly close to the stuiace of the water and have the habit of hovering for a short time over one 

 spot after the manner of some of the other Gomphids. They also frequently alight upon floating logs, 

 bushes, or some v/ater plant. While hovering, the seventh, eighth, and ninth abdominal segments 

 have a decided reddish tinge when the sunlight strikes them just right. 



GOMPHUS AMNICOLA Walsh. 



Gomphus amnicola Walsh, Proc. Acad. Nat. Sci., Phila., 1862, p. 396. 



This species was especially abundant along the banks of the river just above the ponds in series B 

 and was occasionally captured around the fishponds. While the exuviae collected give us the best idea 

 of the actual number 6f imagoes of the various species, the apparent abimdance does not always corre- 

 spond. The present species was seen and captured as often as any other single species, but in the 

 number of exuviae it was far behind most of the other Gomphids. Evidently these imagoes do not 

 migrate after their emergence, but stay around in the immediate vicinity. 



This dragonfly frequents the thick grass and underbrush a little back from the water's edge and 

 can be captured with comparative ease. 



The nymphs and nymph skins were all obtained from the river, and none was found in any of 

 the ponds. 



GOMPHUS NOTATUS Rambur. 



Gomphus notatus Rambur, Ins. Neur., 1842, p. 162. 



This dragonfly is a little larger than amnicola, but has similar habits; it stays out in the open rather 

 more, but is occasionally found in the thick grass. Its favorite haunt is along the river's bank, whence 

 it makes long flights out over the water, returning again to nearly the same place. The nymphs frequent 

 the shallower portions of the river, and none are ever found in the ponds. 



