OF WASHINGTON. 327 



foreign shores, and we should look to the original habitat of 

 these insects for their natural enemies and parasites ; and if these 

 are not already with us, they should be imported. 



THE PHYLOGENY OF HEXAPOUS INSECTS. 



From what I have said, I think I have clearly demonstrated 

 the high rank of the order and its great economic importance, 

 and will now proceed to show its phylogenetic developments 

 and its position among other orders. 



Dr. A. S. Packard, one of our best systematic entomologists, 

 says : " There is nothing like a linear series in the animal king 

 dom, but it is b'ke a tree. The higher series of orders form 

 more of a linear series than the lower series, so that the Neurop- 

 tera, Orthoptera, Hemiptera, and Coleoptera form a more 

 broken series than the Hymenoptera, Lepidoptera, and Diptera. 

 A bee, butterfly, and house-fly are much more closely allied to 

 each other than a beetle, squash-bug, a grasshopper, and a 

 dragon-fly are among themselves." 



This is quite true and a principle now almost universally ac 

 cepted by zoologists. 



Before proceeding with the phylogeny of the Hymenoptera, I 

 shall, therefore, first attempt to show briefly the phylogeny of 

 hexapodous insects, in an ideal genealogical tree. 



This ideal tree is shown on my diagram No. i. 



It will be observed that I agree with Brauer, Packard, Lub- 

 bock, and others in considering the order Thysanura as repre 

 senting the less specialized type of insects and from which de 

 veloped all others, which is emphasized again and again in 

 the larval development of the different orders. 



Twenty distinct orders are recognized, Uratochclia being a 

 new order proposed for the family Japygidae since I believe 

 these insects, although closely allied, are quite distinct from 

 other thysanurians. 



This ideal genealogical tree will, I hope, enable you to at once 

 grasp the affinities of the different orders and will show you the 

 evolution that has taken place in their development. 



It will also demonstrate to you more clearly than pages of 



