INTRODUCTIOX. 15 



the different stages of the larvae to the adult fly, and de- 

 scribe and figure them accurately, will do a good service 

 to science." 



From Dr. Packard, whose original investigations into 

 the metamorphoses of the house fly are so highly appre- 

 ciated by scientific students, and whose publications have 

 done so much toward rendering the study of American 

 insects systematic and popular, I received upon his return 

 from Europe the following: "* * * I am glad you 

 have offered the prize. 1 hope it will elicit a great deal 

 of good observational Mork as to just what good dragon 

 flies and others do in reducing the numbers of mosquitoes. 

 As to house flies, I think that something practical can be 

 done, as the evil is more easily reached, since they breed 

 in stables, and by combined action their number can be 

 diminished. I am sure that the offer of the prize will 

 do a great deal of good." 



After assurlntj; mvself, bv consultation with the highest 

 authorities, that the extensive and artificial propagation 

 and liberation of dragon flics could result in no conceiv- 

 able harm, the following circular was issued : — 



" To THE Working Entomologists of the Country : 

 " Mosquitoes and house flies are, perhaps, the most nu- 

 merous, widely distributed, and persistent of the creatures 

 that attack the health and comfort of human beings. Of 

 their attacks upon our comfort every one is aware. Sci- 

 entific iuvestio-ation favors the belief that tuberculosis and 

 ophthalmia are carried from diseased persons to healthy 

 ones by the house fly, and German experimenters have 

 shown that serious blood maladies may be transmitted 

 by tiie mosquito. 



