90 FIELD AND FOREST. 



direction; or an overturned stone or fragment of bark would reveal 

 frighted Carabidce hastening to get out of sight, but after a few hours 

 collecting it was not an easy matter to find anything strikingly 

 different from the dozen or so species secured in the collecting box, 

 or bottle of alcohol, and when it is considered that we took every- 

 thing that came in our way, making comparison of the result with 

 that of a similar collecting tour in most any portion of Eastern United 

 States, the difference becomes very apparent. 



This was especially marked in regard to the night-flying moths. In 

 addition to our camp-fire, which burned all the evening, candles, pro- 

 tected by canned fruit boxes, served as attraction in various parts of 

 the camp, where they were needed for light, and with the aid of a 

 company of thirty persons, all more or less interested in the collectors, 

 if not in the science of entomology, the entire mountain trip yielded 

 so small a number of noctural Lepidopttra that they are hardly worth 

 mentioning. 



I have had little opportunity to compare notes with other entomo- 

 logists on the subject, but the few with whom I have conversed agree 

 with me perfectly, although I have heard that objection has been made 

 to the statement. 



Lieut. Carpenter's " Notes on the Alpine Insect Flora of the Rocky 

 Mountains," in our last number, would seem to support this view, 

 though he is only considering the insects of the higher elevations ; but 

 the same causes that prevent the possibility of finding more than five 

 species of butterflies in a season's collecting, above timber line, would 

 surely produce like results, though perhaps in a less marked degree, a 

 few thousand feet below. 



In studying the economy of nature we cannot help noticing that in 

 tropical countries, where vegetation grows rank and luxuriant under a 

 burning sun, insects are the most abundant, as they are needed to keep 

 up the balance in nature. In the thrifty farming portions of our own 

 country, we see the same law exemplified ; with extended cultivation 

 of certain plants which man has appropriated to his use, insects feed- 

 ing upon these plants increase and multiply to such a degree that we 

 call them noxious, and should we cease to cultivate these plants for a 

 number of years, the insects would again decrease to numbers so small 

 as to be comparatively unnoticed. 



