322 The Ohio Naturalist. [Vol. XIV, No. 7, 



EXCAVATING THE CAVITY. 



While excavating the cavity, the insect retains a firni attach- 

 ment to the com by clasping the surface, chiefly with the spines 

 on the distal ends of the tibiae. During the entire process, one of 

 the fore legs is in almost constant motion as though endeavoring 

 to obtain a better foothold. The operation of digging is accom- 

 plished by giving an oscillating motion to the thorax on the first 

 pair of legs as an axis, which results in an up-and-down movement 

 of the proboscis. At the same time, the head is turned from side 

 to side, thus adding a rotary motion to the proboscis. This 

 operation continues until the hole is partially dug, when the 

 proboscis is lifted nearly to the surface, after which the sides are 



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■''.■■■■ft'^:'.> 





Figure 1. Longitudinal section of cavity showing egg and plug in place. 



cut down, enlarging the excavation. When the bottom is again 

 reached, the fomicr movements are resumed. These movements 

 often end with sharp jerks as though pieces of the material were 

 being broken off. The work of excavating is continued until the 

 depth of the cavity is equal to the length of the proboscis, when 

 the weevil stops digging, and prepares to deposit the egg. During 

 the process of digging, that part of the proboscis that extends into 

 the cavity is clean, but chewed material collects about the mouth 

 of the cavity and on the portion of the proboscis above. 



