side is below. The head, as already stated, is at the broader 

 end of the egg where the hole is made. Before making 

 the excavation, the H-shaped chitinous plate is brought at a 

 convenient angle and fixed against the egg shell in which 

 process the re-curved teeth of the upper limbs are of consider- 

 able help (Fig. 7). Once the teeth of the plate are fixed, the 

 larva begins operation by working the mandibles alternately 

 or together according as the work is for excavation or for 



Fio. 7.— Larva showing how the chitinous process is fixed against the egg shell. 

 Left side, top view. Right side, side view. Note the radiating grooves 

 made in the egg shell. 



collecting the powder excavated. The chitinous process 

 apparently serves a two-fold object. It stands on a small 

 m^ovable fold of skin which can be rapidly moved back- 

 wards and forwards so that the head may be nearly covered 

 or completely free. When the teeth are fixed against the 

 egg shell far behind, i.e., near its greatest convexity in the 

 thoracic region, the head is freer and the mandibles are 

 engaged in the anterior half of the hole ; when, on the other 

 hand, the posterior half of the hole has to be made, the 

 chitinous structure is adjusted further forwards. In either 

 case, the angle at which the chitinous process is fixed against 

 the egg shell, appears to determine the inclination of the head 

 and consequently the part of the hole that the larva works 

 on at a particular moment. 



To understand clearly why the laiva does not actually 

 bend its head downwards as one might expect it to do in 



