NO. 1692. DRAGONFLIES OF THE MISSISSIPPI VALLEY— WILSON. 



10 miles above Grafton and the other 4 miles farther up the river. 

 These have already been referred to on page 667. 



This isolation of species into colonies prevailed throughout the 

 entire length of the various rivers visited and in some of the small 

 lakes. It is a very different condition from what is found in other 

 lakes where fifteen or twenty species, or even more, can be secured in 

 a single afternoon ; witness Lake Amelia and Lake Phalen. It leads 

 naturally to the next conclusion — 



5. With the exception of such genera as Gomphus and Anax and 

 such species as Lihellula pulchella Drury, the individual range of any 

 dragonfly or damselfly is in all probability very small. 



The members of one of these colonies just noted are probably 

 natives of the locality. They were born there, they spend their lives 

 in hunting the insects that surround the water, they lay their eggs in 

 the same water, and then die. Continued observation of such a 

 colonized area for many years would doubtless reveal much that 

 would be of interest in its bearing upon colonization in general, as 

 well as upon the distribution of species. 



