60 Belladonna Leaf- Miner 



the best chance of completing their development. If, in the course of 

 their activities, they undermine the mesophyll layers beneath a bundle 

 of un hatched eggs, the larvae issuing from the latter do not attempt 

 to enter the leaf where the epiderm has been loosened, but they search 

 about for a part that is fresh and untouched. Often they die before 

 they succeed in fulfilling their mission, and, indeed, sometimes the eggs 

 do not hatch at all. The exact reason for this it is not easy to find. 

 Perhaps it may be that they merely undergo desiccation owing to the 

 discontinuance of the respiratory functions of the injured part of the 

 leaf. The incurrent and excurrent streaming of moisture-bearing gases 

 through the leaf-stomata, which would, in the natural course of events, 

 maintain an atmosphere sufficiently humid for the successful develop- 

 ment of the embryo in the egg is totally checked, with fatal results. 



No definite information has been previously given of the duration 

 of the various larval stages of which there are undoubtedly three, and 

 the statements also of the different authors of the length of the complete 

 larval and pupal stages are apparently in disagreement. But this 

 seeming inconsistency is quite comprehensible when one considers that 

 the times may vary in multi-brooded species depending on the season, 

 according as it is the first, second or third brood, and further because 

 of the climatological conditions which prevail in dift'erent countries 

 as well as in different districts of the same country. 



As indicated previously in the description of the larva, there are at 

 least two moults and three distinct stadia. Carpenter (p. 290) suggests 

 the probability of there being four moults, but I have not been able to 

 verify this additional one which he assumes as intervening in the last 

 larval stadium. During the month of June the larva completed its 

 development in about ten days. Later in the year, during September, 

 as many as twelve days were required. Where incidental circumstances 

 are favourable, the times of the various larval stages are approxi- 

 mately twenty-four hours for the first, forty-eight hours for the second 

 and seven days for the third. 



It is interesting to note the time occupied by the larvae of the 

 different stages in making an entrance into a fresh leaf when placed upon 

 its surface. In some cases they get to work rapidly. Often they keep 

 wandering restlessly here and there. The following are three authen- 

 ticated cases, the facts of which were noted on June 23rd. 



(1) Three larvae recently emerged were removed to a fresh leaf. 

 After a few sluggish efforts to pierce the epiderm, which occupied an 

 hour, they gave up the attempt. Even when a tiny puncture was 



