BARK-BEETLES; ENGRAVER-BEETLES. 



223 



structed by the female beetles, extend rather deeply into the wood, 

 with their branches mostly in a horizontal plane (Fig. 236). 



"The mother beetle deposits her eggs singly in circnlar pits 

 which she excavates in the gallery in two opposite series, paral- 

 lel with the grain of the wood. The eggs are loosely packed in 

 the pits with chips and material taken from the fungus bed, which 

 she has previously prepared in the vicinity, and on which the am- 

 brosia has begun to grow. 



Fig. 236.— Burrows of Monartbruta mali, Fitch. After Division of Entomology, 

 U. S. Department of Agriculture. 



"The young larvse, as soon as they hatch, eat the fungus 

 from the chips, and eject the refuse from their cradles. At first 

 they lie curled up in the pit made by the mother, but as they grow- 

 larger they deepen their cradles with their own jaws, until, at 

 full growth they slightly exceed the length of the larva when 

 fully extended. The larvie swallow the wood which they exca- 

 vate, but do not digest it. It passes through the intestines un- 

 changed in cellular texture, but cemented into pellets by the ex- 

 crement, and is stained a yellowish color. The pellets of excre- 

 ment are not allowed to accumulate in their cradles, but are fre- 

 quently ejected by them, and are removed and cast out of the 

 mouth of the boring by the mother beetle. A portion of the ex- 

 crement is evidently utilized to form the fungus garden bed. The 



