1919 



ENTOMOLOGICAL SOCIETY. 



37 



brown-tail moths — preferably something with two or more generations a year 

 so as to insure a rapid increase. We also needed something that would develop 

 its greatest usefulness against the Brown-tail Moth while that host was still 

 relatively scarce. All these attributes were possessed by C ompsilura and the work 

 of importation began with hopes running high for the success of the venture. 

 What we did not know, of course, was whether this fly could live under boreal con- 

 ditions, where the climate is so much more erratic and severe than in France and 

 Massachusetts. 



Seven years ago, in 1912, two colonies of Compsihira were liberated in New 

 Brunswick strong enough and under good enough conditions to warrant recovery 

 speculations. The next year, however, no Conipsilura could be recovered from 

 the colony sites and the work of importation had to be continued. At first there 

 was no occasion to worry about the non-recovery of Compsilura, for it had taken 

 three years to prove establishment in the United States. However, being human 

 we worried a little and increased our efforts to secure more material for liberation. 

 After four years of colonization, without apparent results, we redoubled our efforts 



Fig. 3. — Abdomen of female ComiisUura shcv- 

 ing piercing device. Tlie ventral part of seg- 

 ments 2, 3 and 4 is flattened into a keel 

 shaped structure. Note the clusters of spines 

 on segments 2 and 3 that have been 

 developed for holding the caterpillar when 

 using the piercer. (Original.) 



Fig. 4. — Piercing device of 

 female Compsilura. With 

 this hollow, sickle-shaped 

 instrument (1 mm. in 

 length), the female fly punc- 

 tures the skin of a cater- 

 pillar. With her somewhat 

 inconspicuous larvipositor 

 she then places a maggot 

 in the wound after which 

 she flies to another victim. 

 (Original.) 



to secure a large number of flies. Host caterpillars were collected in great quanti- 

 ties in Massachusetts and a very large number of the flies were bred out for 

 liberation, as the chart shows, in Nova Scotia, New Brunswick, Quebec and Ontario. 



At the close of that year, 1916, it was felt that every opportunity had been 

 given Compsilura to become a part of the Canadian fauna — in a period of five 

 years about thirty thousand flies had been liberated — and the work of importation 

 was consequently stopped. 



In 1917 a considerable amount of energy wes expended in the attempt to 

 recover this elusive fly, but once again the results were discouraging. This year 

 (1918) the recovery work was continued and the in sectary at Fredericton filled 

 with thousands of tussock, datana, and red humped larvte, collected from' likely 

 places in Nova Scotia and New Brunswick. One day Mr. Keenan, who had charge 

 of the tray work, brought in several dozen tachinid puparia bred from tussock 

 larvffi collected at Fredericton. Among these were five little puparia that had the 

 ear marks of Compsilura. With the same sort of tender solicitude that worker 

 ants bestow upon larvas just stolen from a nearby colony, we watched over these 

 five puparia. After a week' or two of anxious waiting five flies emerged; three 

 were males and two females and all were Compsilura concinnata. 



