DISTRIBUTION OF TIGER BEETLES. 1 3 



open places of the black oak ridges. These oaks are destined not to 

 remain and are crowded out by the coming- in of the white oaks. 

 For an immense period after this, the habitats of C. scutellaris 

 become more and more narrowed. Long before the next tree, 

 the red oak, makes its appearance, C. scutellaris has been crowded 

 out. Many centuries must pass between the coming in of the 

 white oak and the establishment of the red during much of which 

 time the Cicindelas are entirely absent. With the establish- 

 ment of the red oak, conditions are ready for the next tree, the 

 shag-bark hickory, and with it comes C. sexguttata. This species 

 appears to reach its dominance in the early stages of the white 

 oak-red oak-hickory forest, and to be crowded into its margins 

 with the development of further mesophytism. It continues in 

 the roads, clearings, fired places, and paths of cyclones in this 

 forest for a long period. Individuals are sometimes to be found in 

 the dense parts about a fallen tree. This type of forest is, how- 

 ever, destined to disappear and its disappearance is heralded by the 

 coming in of the seedlings of the beech and the maple. With 

 their appearance C. sexguttata becomes rare in the forest proper. 



This species does not deposit eggs in pure humus, but makes 

 use of little irregularities in clay or sand, which, contains a little 

 humus and which is shaded slightly, such conditions as are 

 afforded by falling trees and the erosion of hill sides by small 

 brooks. It prefers a few loose leaves and will lay eggs under 

 them in preference to other places when they are present. It 

 does, not, however, appear to like very shady conditions. Several 

 days spent in the beech and maple forest has failed to reveal the 

 presence of one of these insects although they were present in 

 open and partially cleared places a short distance away where 

 the forest has not become so mesophytic. 



The beech and maple forest is very shady and has a floor of 

 decaying leaves about one inch deep and several inches of very 

 mouldy humus below these, so that there is no place in the 

 forest proper where C. sexguttata can deposit eggs. It is driven 

 out by the development of these conditions. 



The white oak-red oak- hickory forest is now distributed over 

 much of the eastern half of northern North America, but the 

 climate in which the beech and maple will develop extends west- 



