NATURE STUDY. 
58 
it the sand and a few pebbles, causing the gravel above to 
slide down. This in turn was carried away and more came 
down in its place. The angle of the banks would be that 
at which the sand of the given compactness would remain 
at rest. The little, eroded valley increased in length as 
well as in breadth. 
As we look at it today we see the results of nature’s carv 
ing. The steep banks of sand that send down tiny land¬ 
slides as we walk along, the bowlders and pebbles at the 
bottom, all show how the water worked. This is a min¬ 
iature of the work that is going on wherever the waters are 
carrying sand and silt down from the mountains to the sea. 
It is an example at home, perhaps in our own door yard, of 
nature at work. It is worth a visit and study. 
Life upon a Rose Bush. 
BY SUSY C. FOGG. 
Upon the morning of May 8th I went to the garden, to 
find the rose bushes covered with swarms of shining black 
flies, trim and graceful in appearance, and evidently be¬ 
longing to the Hymenoptera. They lingered fondly about 
the branches, and even when disturbed would fly but a 
short distance and alight again, always on the rose leaves. 
This decided preference convinced me that they were there 
for no good. Upon closer examination I found that I pos¬ 
sessed in large numbers the Monostegia rosae, or rose-slug, 
of Comstock, and Selandria rosae of Harris, of the family 
Tenthredinidae, or Saw-flies. The insect was new to me 
in its matured form, but its family is nearly as “ old as the 
hills,” and this time, it seems, infinitely less respectable! 
In the year 1832 it was observed in gardens in Cam¬ 
bridge, but Harris writes that at that time it had not 
