Destructioe Insects and Utility of Birds. 
239 
caterpillars were greatly lessened, and in ISilO my little winged gardeners liad 
so well cleansed all my trees, that, thanks to their labour, I had the satisfaction 
of seeing them in full leaf the whole of the summer." 
The indefatigable wren, which remains with us during the 
winter, is of very great use, for its appetite equals its activity. 
They must perpetually be swallowing something, and accustom 
their young to follow their example in gluttony, by feeding them 
on an average, thirty-six times every hour with insects' eggs, 
larva?, &c. A hungry redstart (^Sylvia tithys) captured in a 
room, during the space of an hour, 600 flies ; and if this little 
animal hunts but for two or three hours a-day, we may guess the 
number of its prey. The swallow and the martin (^Cypselus) in 
the davtime, and the European goat-sucker (Caprimulyus Euro- 
pceus) during the night, capture swarms of gnats ; the chaffinch, 
the jay, the jackdaw (Corvus monedula), devour the Lasiocampa 
and Noctua. Even sparrows may be included in the list of 
useful birds, notwithstanding the damage they cause at times to 
the orchard or corn-field, because they feed their young (which 
have very good appetites) exclusively upon larva?, grasshoppers, 
caterpillars, beetles, worms, or ants ; and both old and young at 
the end of summer are constantly filling their crops with the 
seeds of weeds. A couple of sparrows will consume in food for 
their young about 3000 insects weekly, each parent bringing a 
billful thirty times an hour. These services are well worth a few 
cherries. The field-sparrow does not, moreover, eat cherries, and 
a small number of these birds will soon cleanse many shrubs and 
rose-trees from the aphis. 
Frederick the Great, king of Prussia, being very fond of 
cherries, one day ordered a general crusade against the sparrow 
tribe, some of them having ventured to peck at his favourite 
fruit. A price of 6 pfennings a brace was set on them ; conse- 
quently throughout Prussia the war was briskly carried on, and 
so successfully that at the end of two years not only were cherries 
wanting, but most other fruits. The trees were covered with 
caterpillars, and completely stripped of leaves ; insects had 
increased to a most alarming extent, for other birds had been 
frightened away by the extraordinary measures taken mainly 
against the sparrows. The great king was obliged to confess to 
himself that he had not the power to alter that which had been 
ordained by a still greater King than he, and that all attempts at 
violence and wrong were sooner or later avenged. He retracted 
his decree, and was even obliged, at a considerable expense, to 
import sparrows from afar ; for these being birds of obstinately- 
sedentary habits, Avould never have returned of their own accord. 
When field-sparrows feed in a corn-field they ought merely to be 
warned off, not killed, unless, indeed, there be many insecti- 
