INSECT-ARCHITECTURE. 183 



these in Europe (Psyche helix) constructs a snail-like case. 

 Beetle-grubs rarely construct such cases, but the little 

 Chlamys is a genuine sack-bearer, as is another leaf-eater, 

 Coscinoptera dominicana. 



All the Caddis-flies are sack -bearers in their larval state, 

 and the larvas are from this habit called case-worms. The 

 worm apparently builds them by adding grain after grain 

 of coarse sand to the mouth of the tube, lining the interior 

 with silk; if there is moss at hand, bits are fastened to the 

 exterior, or large pieces of leaves. Fig. 233, a, represents 



a 



FIG. 233. Different forms of cases of caddis-flies. 



the case of the European Phryganea grandis; but we have 

 a similar one, formed by cutting a leaf into a broad ribbon- 

 like strip and then rolling it into a tube. Some are like 

 horns, while the case of Helicopsyche (Fig. 233, d) has often 

 been mistaken by shell-collectors for a fresh-water snail 

 (Valvata). 



As architects ants are preeminent, and they evince their 

 skill in construction not by mounds alone, but also by 

 digging deep wells and tunnelling broad rivers, as well as 

 in laying out roads above and below ground. 



While our native species are not known to form elaborate 

 nests, a greenish ant in India ((Ecophylla smaragdinci) is 



