HOW TO MAKE A COLLECTION. 29 
species of handsome butterflies were no less numerous. At the 
approach of any one they rose in a swarm, some resting on the 
sides of the old mill, while others continued to fly until the danger 
was past and then settled once more to the feast. It would be diffi- 
cult to tell which occupied the greater part of my attention, the but- 
terflies or the cider. Suffice it to say, that both I and my collecting- 
jar went home pretty nearly full after a few hours passed at the old 
cider-mill. 
The tops of hills and low mountains are frequented by butterflies ; 
and often when the sides of a hill are poor in both species and indi- 
viduals, they will be found plentifully on the tops, especially if there 
is a cleared space in the forest occupied with shrubs and bushes 
where they may fly about. At such times they may be seen flying 
in revular circuits, and two or three will often chase each other up 
into the air until they are almost lost to view. 
I remember such a hill near Sonora in California. Starting with 
a fellow-collector early in the morning of May 15th, we arrived 
at the top of the hill about nine o’clock. We had seen few butter- 
flies on the way up: but on reaching the top, we found them in 
hundreds. The air was filled with them, they rested in dozens on 
every bush. There were not a great many species, perhaps not more 
than seven or eight kinds in all; but of these we could have taken 
almost any number, and I caught two cigar boxes full of perfect 
specimens — perhaps two hundred and fifty insects — before dinner 
time. A large number were imperfect; and we found a good many 
dead and dying ones on the rocks and ground. The lizards and ants 
were making great havoc among the weak and sickly ones, and the 
ground was littered with their wings. Why they had so congregated 
I cannot imagine. The gentleman with whom I went informed me 
that he had found them in this place several years in succession, at 
the same season of year. 
The different species of Parnassius are mountain-inhabiting but- 
terflies, and are usually found far up on the sides of high mountains. 
We have several mountain butterflies which are to be found upon 
the bare and inhospitable tops of the White Mountains in New 
Hampshire. Mountain valleys are usually very rich in butterflies ; 
and on a road traversing such a valley the collector will sometimes 
find a veritable paradise for his labors. 
Some butterflies are very combative, and will give chase to every 
flying object that comes in their neighborhood. ‘They will even fol- 
