inordinately, their natural enemies have increased in the same
proportion, and thus preserved the balance.--_Ibid_.


_Gnats_.

There are few insects with whose form we are better acquainted than
that of the gnat. It is to be found in all latitudes and climates; as
prolific in the Polar as in the Equatorial regions. In 1736 they were so
numerous, and were seen to rise in such clouds from Salisbury cathedral,
that they looked like columns of smoke, and frightened the people, who
thought the building was on fire. In 1766, they appeared at Oxford, in
the form of a thick black cloud; six columns were observed to ascend the
height of fifty or sixty feet. Their bite was attended with alarming
inflammation. To some appearances of this kind our great poet, Spenser,
alludes, in the following beautiful simile:--


As when a swarm of gnats at eventide,
Out of the fennes of Allan doe arise,
Their murmurring small trumpets sownden wide,
Whiles in the air their clust'ring army flies.
That as a cloud doth seem to dim the skies:
Ne man nor beast may rest or take repast,
For their sharp wounds and noyous injuries,
Till the fierce northern wind, with blustering blast,
Doth blow them quite away, and in the ocean cast.


In Lapland, their numbers have been compared to a flight of snow when