to be considered as i?idigenous, 1 55 



tlality for any other food; and yet, from its not unfrequent 

 appearance in the north of Germany in particular years, as 

 well as in other parts of the Continent, where that beautiful 

 plant requires careful protection from the severity of the 

 winters, it is to be presumed this magnificent moth has some 

 more abundant pabulum to resort to as a derfiiere ressource, 

 when compelled to forage in its native haunts, perhaps the 

 VincsL major, minor, or some species of Cynanchum, all 

 belonging to the same natural family of .^pocyneas. Few 

 polyphagous larvae are restricted to one natural family of 

 plants for subsistence ; but, were that the case, the soil might 

 furnish an acceptable treat to the subjects of the present dis- 

 sertation in our two indigenous >Solana, our henbane, deadly 

 nightshade, Ferbascum, or naturalised thorn-apple, while 

 ^phin^ Drur<^V would probably feel quite at home making 

 a meal on our gracefully twining bird weeds. 



To infer the exotic origin of any insect merely from the 

 foreign growth of the plant it feeds on, is an argument much 

 on a par with one that should go to prove the present in- 

 habitants of Wales unconnected by descent with the ancient 

 Britons, simply because thej^ no longer subsist like their an- 

 cestors on the spontaneous productions of their woods and 

 forests. 



Having thus endeavoured to solve the enigmas which 

 these monsters of the insect race, like their prototj^pe of old, 

 have propounded to modern QEdipi, I shall conclude this 

 dissertation with a short summary of my ideas respecting the 

 propriety or impropriety of admitting into our lists of indi- 

 genous insects such as are recognised as inhabitants of other 

 and distant regions. We may do this, it appears to nie, with- 

 out risk of confusion, — 



1. Wlien an insect is known to inhabit countries pretty 

 similar in climate, and having nearly the same mean temper- 

 ature with that in which it has been found at large, as is the 

 case with the southern part of Great Britain and the middle 

 portion of the United States ; though the average of each 

 season, taken separately, differs widely in the old and new 

 continent. 



2. When the same insect has been repeatedly taken in 

 distant localities ; sometimes in pairs, and especially when it 

 has appeared in the larva state. 



3. When the appearance of such insect cannot be ac- 

 counted for, except in a manner very problematical and 

 unsatisfactory. 



On the other hand, we must regard such insects with 

 suspicion as — 



