he minor evil of being nearly suffocated
by smoke is endured to get rid of these little pests. Captain Stedman
says, that he and his soldiers were so tormented by gnats in America,
that they were obliged to dig holes in the ground with their bayonets,
and thrust their heads into them for protection and sleep. Humboldt
states, that "between the little harbour of Higuerote and the mouth
of the Rio-Unare, the wretched inhabitants are accustomed to stretch
themselves on the ground, and pass the night buried in the sand three
or four inches deep, exposing only the head, which they cover with a
handkerchief."

After enumerating these and other examples of the achievements of the
gnat and musquito tribe, Kirby says, "It is not therefore incredible
that Sapor, King of Persia, should have been compelled to raise the
siege of Nisibis by a plague of gnats, which attacked his elephants and
beasts of burden, and so caused the rout of his army; nor that the
inhabitants of various cities should, by an extraordinary multiplication
of this plague, have been compelled to desert them; nor that, by their
power of doing mischief, like other conquerors who have been the torment
of the human race, they should have attained to fame, and have given
their name to bays, town, and territories." _Ibid_.

_Leaf Caterpillars_.

The design of the caterpillars in rolling up the leaves is not only to
conceal themselves from birds and predatory insects, but also to protect
themselves from the cuckoo-flies, which lie in wait in every quarter to
deposit their eggs in their bodies, that their progeny may devour them.
Their mode of concealment, however, though it appear to be cunningly
contrived and skilfully executed, is not always successful, their
enemies often discovering their hiding place. We happened to see a
remarkable instance of this last summer (1828), in a case of one of the
lilac caterpillars which had changed into a chrysalis within the closely
folded leaf. A small cuckoo-fly, aware, it should seem, of the very spot
where the chrysalis lay within the leaf, was seen boring through it with
her ovipositor, and introducing her eggs through the punctures thus made
into the body of the dormant insect. We allowed her to lay all her eggs,
about six in number, and then put the leaf under an inverted glass. In a
few days the eggs of the cuckoo-fly were hatched, the grubs devoured the
lilac chrysalis, and finally changed into pupae in a case of yellow