THE MARGUERITE FLY. 27 



two yellow marguerite plants kept under observation in the insectary, one 

 did not bloom until June (the plants were received early in February), 

 when the flies in the house had decreased and the attack had considerably 

 abated, while the other produced no flowers at all — at least up to July 5, 

 when the writer left Amherst for the summer. Buds in many instances 

 formed, but they dried up after reaching a certain size. The following 

 December the two yellow marguerite plants were dead. 



IMPORTANCE OF THE PEST. 



The wide distribution of the insect, the large number of commercially 

 grown plants it attacks, the numerous complaints, — many of these re- 

 porting serious injury, — all attest and bear testimonj'- to the seriousness 

 of its depredations. 



As far back as 1890, Mr. J. H. Ives of Danbury, Coim., writing to 

 Coquillett of the federal division of entomology, stated that he would be 

 compelled to abandon the growing of such plants as marguerites and 

 feverfews, owing to the attack of this pest. 



According to Britton (1911) the damage in Connecticut has been so 

 great in some instances that the growers had to abandon the commercial 

 growing of such plants as chrysanthemums, marguerites, feverfews, ciner- 

 arias, eupatoriimis and tansies. 



Sanders (1912), in reporting an outbreak in Wisconsin, states that the 

 growers were facing an entire loss of their flowering plants caused by a 

 complete infestation of the leaves. 



Mr. Walker Holden, in reply to a letter of the writer, closes as follows: 

 ''I shall be very glad to help out in any way I can to conquer this pest, for 

 it is surely a pest." 



Fortunately, no great fears, it seems, need be entertained in regard to 

 the insect as an outdoor pest, it appearing to be essentially an indoor or 

 greenhouse insect. If- provided with food, it will remain in the greenhouse 

 all summer, although in reduced numbers. In addition to its being 

 essentially a greenhouse pest, it is apparently also essentially a moderate- 

 temperature insect, seeming to find its most congenial conditions in a 

 temperate and somewhat humid atmosphere. The writer had noticed a 

 considerable falling off in its numbers even before he left Amherst for the 

 summer (first week in July). This could not be explained entirely on 

 the ground that some had left the insectary to take up an outdoor existence, 

 for those that left apparently remained in the vicinity of the insectary, 

 and their numbers could therefore be observed. The hot, sunny, dry 

 atmosphere in the insectary, it seems, is a much better explanation of the 

 decrease. Such an environment may cause itself to be felt in a number 

 of ways. It may diminish the egg-laying powers of the female; it may 

 cause a reduction in the percentage of eggs hatching; it may cause 

 the death of certain larvae (the writer found both eggs that failed to 

 hatch and dead larvse in a number of instances in late June), etc. It is 



