48 
variety of waters containing vegetation, and even where other 
species of nymphs are largely wanting. Lakes, rivers, ponds, 
swamps, transient pools, small ditches, springs, throughout the 
state,—all produce a crop of these nymphs. ‘This fact together 
with their active habits and voracity, would indicate a rapid 
development. Kellicott states that from an excavation for an 
artificial lake, which was filled up with water in early May, 
largenumbers of junius imagos emerged in late August, indicat- 
ing the occurrence of two broods ina year. This is confirmed 
by one of our experiments, half-grown larve placed by Mr. 
Hart in a breeding-cage June 16 reaching the imago stage 
August 4. A noticeable reduction in the number of large 
nymphs and an increase of the younger ones about July 1 has 
been recorded in two different years. Young predominate in 
our October collections, and those taken early in spring are 
mostly of large size. The imagos attain greatest abundance in 
May. On May 19, 1894, the abundance of fresh exuvize was con- 
sidered worthy of record. 
According to Kellicott this is the first dragon-fly abroad in 
early spring, remaining until the middle of October. Several 
pairs were seen by him flying in union March 21, the female 
ovipositing. In early spring, according to Mr. Needham, the 
eggs are deposited in the water-soaked stems of reeds, in float- 
ing sticks, pieces of board, etc.; while later in the season they 
are placed in the green and growing stems of aquatic plants. 
He states that the females are usually held by the males during 
oviposition, and often descend into the water for this purpose. 
The imagos wage a ceaseless warfare on gnats, mosquitoes, 
and other small winged insects. In August, writes Mr. Need- 
ham, I saw a small swarm (more than a score) moving together 
through an orchard in Cass county, I1]., miles from open water. 
At the same place a few days later, during three successive 
days of high wind, Anax junius and Tramea lacerata could 
always be seen hovering in the lee of orchard trees, grape 
arbors, stacks of grain, etc., circling swiftly several rods away 
from shelter then beating slowly toward it again, head to wind, 
