ILLINOIS HORTICULTURAL SOCIETY. 2G1 



■when we remember that at most, only a dozen or so of these flies were 

 let loose in three different orchards, each of which contained several 

 hundreds of trees, some idea may be formed of the dehcacy of this 

 experiment, and of the difficulty of determining with certainty whether 

 it had succeeded. 



In May, 1872, a little more than a year after the commencement of 

 the experiment. Captain Ueebe carefully examined the trees upon 

 which the chalcis larvae had been placed, and discovered and transmit- 

 ted to me for examination a number of twigs, some of the scales upon 

 which exibited the characteristic round holes caused by the exit of the 

 chalcis fly. In July, of the same year, I visited Galena, and in company 

 with Capt. Beebe, submitted one of the trees experimented upon to a 

 pretty thorough examination. Additional traces of the chalcis flies 

 ■were discovered, and still others were sent to me by Capt. Beebe later 

 in the season. 



The success of this interesting experiment may therefore be said to 

 have been proved as nearly as any exijeriment of this kind can be, 

 within so short a period after its commencment. If it shall be found 

 by future investigation that similar marts exist in other localities at 

 a distance from those experimented in, the jjresumption will then be 

 that either this or some other species of chalcis, had already found its 

 way in small numbers to these more northern sections. But if, on the 

 other hand, these marks shall be found to become more numerous, 

 year by year, in the neighborhood of this experiment, whilst they shall 

 not be found at a distance from it, the success of the experiment may 

 be considered as demonstrated. 



If future observations shall confirm the success of this experiment 

 which already presents so encouraging an aspect, every one will admit 

 that it will furnish one of the most interesting instances on record of 

 the application of science to practical purposes. 



This experiment of transporting and colonizing the beneficial para- 

 sitic insects, is therefore not only a very important one in itself, but it 

 derives additional interest from its being, so far as I am aware, the only 

 one of the kind which has ever been attempjted, and I am hapj^y to have 

 the opportunity of contributing this sketch of it to the transactions of 

 the Northern Horticultural Society of Illinois. 



The lecturer then gave a brief sketch of the history and treatment of 

 the canker worm, which has been particularly destructive for a number 

 of years past in several of the northern counties of this state. But 

 these remarks were made without written notes, and the substance of 

 them has been already published in the author's second annual report 

 upon the injurious insects of Illinois. 



In response to questions, Dr. LeBaron replied, that the female can- 

 ker worm, being wingless, is very localized, in comparison with other in- 

 sects. It spreads principally by being carried on clothing and the va- 



