45 



W. F. Melcheimer, as early as the year iSoi, but appears 

 to have become extinct. It was collected by Mr. Bolter, 

 about Chicago, and by Mr. Walsh, near Rock Island, 

 Illinois, some 25 or 30 years ago, but has, as far as known, 

 not been observed in that part of the countr}' since. Within 

 the last ten years it has established itself in Northeastern Ohio, 

 and appears to be slowly but surely pushing its way west- 

 ward, though just why it should be any better able to sus- 

 tain itself than before is not clearly apparent. So far as my 

 own observations have gone, this inst'ct does not first appear 

 in the cultivated patches of asparagus in a locality, but on 

 isolated plants in waste places, which plants have escaped 

 from cultivation, and in this half wild condition are known as 

 "volunteer" plants. I understand that this is also true of the 

 insect in the east, and the lack of these volunteer plants, at 

 an earlier period, might have prevented its previous perma- 

 ment establishment. So far as I have myself observed, 

 Murgantia histrionica usually attacks some species of wild 

 Crucifer^e, and spreads from this to the cultivated plants. 

 At least I have observed this to be the case where it was 

 just appearing in a locality, and leads to the suspicion that 

 foreign species, in their diffusion over the country, act very 

 much in the same manner as native species, when adapting 

 themselves to a change of environment, and even the most 

 careful collecting may not reveal their presence, even when 

 they have for years been present in greater or less numbers. 

 I remember, in collecting Coleoptera in Illinois, Hister bima- 

 ctdatus Linn., was very rarely met with, until I found upwards 

 of a hundred specimens at one time, under a small pile of 

 stable manure. This was fully twenty years ago, and when 

 it was probably moving across the State in its westward 

 march. It has always appeared to me that this was the 

 most serious difficulty in the way of mapping out life zones, 

 as is at present becoming quite popular. The data, upon 

 which the area covered by such zones is based, is more or 



