584 VICTOR E. SHELFORD 
It is not to be understood that these forms are in any way 
directly related to the trees, but the trees represent the general 
conditions in which the beetles will live and reproduce. The 
species is an inhabitant of one of the ‘climatic’ realms and will 
be found continuously distributed where the forests are con- 
tinuous. 
6. Geographic variation in life-history. C. sexguttata rarely 
appears in northern localities in the autumn and it is probable 
that it remains in the pupal burrows until spring. The species 
is reported as appearing both autumn and spring in some southern 
localities. At Chicago, the adults appear during April and May, 
while in the western part of the geographic range of the species 
they do not appear until late in June, after the heavy rains which 
soften the soil, so that the imagoes can dig to the surface. 
d. Other species 
1. Experimental studies of habitat selection. By similar 
methods, I have determined the breeding place of the following 
species: C. scutellaris, high, dry sand with a little humus, or 
sand which is not shifting; C. formosa generosa, slightly shifting 
sand; C. lepida, shifting white sand; C. duodecimguttata, very 
moist dark soil; C. punctulata, soils with some humus and moist at 
egg-laying time; C. purpurea, same as punctulata, but in moister 
places, not repelled by considerable grassy vegetation, bare spots 
necessary as breeding places. In every case the range of the 
adults is far wider than the breeding grounds. 
2. Geographic variation in habits. In captivity the larvae of 
all the species studied at Chicago close the burrows near the mouth 
and go to the bottom when the soilis dry. Here they remain inac- 
tive until water is applied. No such closures have been noted in 
the field, except C. lepida, which lives on the dry sand dunes. 
Criddle (’10) says: 
In Manitoba, there are often long intervals of inactivity of the larvae 
of manitoba, venusta, limbata, lecontei, and probably others, during 
the summer months. At such times the larvae close their burrows at 
