INSECT NESTS — SJOSTEDT. 345 



is flattened and notched, it loosens a fragment large enough to make 

 up the future ball; then with a rapid movement the ball is freed and 

 rounded off. Then standing on its front feet the scarab with his back 

 feet rolls the ball thus made. During this operation the insect dis- 

 plays great activity, but at this stage others of its kind endeavor to 

 get possession of the fruit of its toil. A struggle ensues, during 

 which the ball changes owners several times, and the final victor 

 endeavors then to get the ball away in safety either for its own use 

 or for that of its larvse. 



In the case just cited the parents provide shelter and reserve nour- 

 ishment for the evolution of the larvae, while among other species the 

 larvae themselves provide their own nourishment and a way of release 

 when the transformation is complete. 



Among the cicadas, which live in the Tropics and contribute their 

 song to the perpetual concert heard there during the dry season, the 

 larvae at the time of being transformed into perfect insects bury 

 themselves about 40 centimeters deep in the earth. In digging the 

 hole they secrete a liquid which assures the permanence of the pas- 

 sage by hardening the sides. The quantity of liquid required to coat 

 this tube nearly half a meter long is considerable, and the insect 

 would not have enough unless while digging it encountered new ma- 

 terial to supply the secreting organs. A close examination of the 

 nest shows the presence of roots laid bare, from which the insect 

 draws the sap by means of his proboscis. This nest, consisting of a 

 shaft sunk in the ground with solid walls, permits the insect to come 

 to the surface during the warm hours, and to bury itself to escape the 

 cold. 



IV. 



An unusual method of making nests is encountered among cer- 

 tain ants — those which build their nests in galls. On the plains of 

 eastern Africa attention is often attracted to small acacias with long 

 thorns appearing from a distance to be covered with a great number 

 of black balls resembling apples but which in reality are hollow galls 

 inhabited by a species of small ants, Cremastog aster tricolor. If one 

 of these galls is touched, all the inhabitants come out through a se- 

 ries of small orifices, and from the extremity of their abdomens, 

 raised vertically, flows a white, ill-smelling liquid, with which the 

 galls, leaves, and branches become saturated. 



The young galls are green in color, with a solid interior, attain- 

 ing sometimes the size of a walnut. The ants remove little by little 

 the medullary substance in such a way that the interior of the gall 

 becomes a chamber with smooth and polished walls. The gall then 

 takes on the color of soot and has a ligneous texture. When the wind 



