Walter Ritchie 335 



full-grown larvae were examined at intervals, but no signs of pupation 

 were shown. From January, 1918, to April, 1918, they were not examined, 

 as during this period I was engaged in Forest Survey work for the Board 

 of Trade Timber Supply Department. On May 16th, 1918, 1 re-examined 

 these stems but still there were no signs of pupation. On May 22nd, 1918, 

 the first larva pupated; others continued to pupate up to June 1th, 

 1918. 



The larval period then from July 10th, 1916, to May 22nd, 1918, was 

 about 23 months. When emergence of the adults was near at hand, the 

 stems were screened with slips made from draper's cotton so that the 

 adults when they emerged from the stems would not escape into the 

 open; the adults were secured. The adult stage was reached by one 

 female on July 2nd, 1918, but she did not emerge through the exit hole 

 till July 14th, 1918. That is to say, the pupal stage from May 22nd, 1918, 

 to July 2nd, 1918, lasted about forty days. Many adults, the majority 

 of them males, issued from the stems up to July 31st, 1918. As these 

 adults came away from the stems and collected in the cotton slips they 

 were caught and placed in fresh cotton cages. Each cage consisted simply 

 of a slip of cotton drawn over each of the four uninfested transplanted 

 stems already referred to. As the foliage of the trees could not be en- 

 closed conveniently within the cotton cage, each slip at its upper end 

 was tied closely round the stem, while the lower end of the slip next the 

 ground was weighted down with stones and soil. In this way a com- 

 plete cage was formed and the beetles could not escape. In each cage 

 a wide-necked bottle of water was enclosed, containing young twigs 

 bearing leaves of the Trembling Poplar (Populus tremula Linn.), so that 

 the beetles could feed on the leaves if they chose. Fresh twigs were 

 placed in the bottles in the cages every second day. Immediately the 

 beetles were placed in the cages they made for the leaves on the twigs 

 and greedily devoured them. 



The first pair of beetles was placed in a cage on July 16th, 1918, and 

 a constant watch was kept for pairing, but copulation did not take place 

 till July 26th, 1918, the beetles having fed for eleven days. As soon as 

 pairing was observed, the pairs were marked by simply breaking off 

 the tip of an elytron, so that they could be readily recognised. Three 

 days after having paired, the first male beetle died. Oviposition of the 

 first female was noticed to take place at the base of the stem enclosed 

 in the cage, on August 2nd, 1918, and egg-laying was completed by 

 August 15th, 1918. As soon as egg-laying was completed the female no 

 longer fed on the fresh leaves supplied, but clung to the sides of the 



