Little Fly,
Thy summer's play
My thoughtless hand
Has brushed away.

Am not I
A fly like thee?
Or art not thou
A man like me?

For I dance
And drink, and sing,
Till some blind hand
Shall brush my wing.

If thought is life
And strength and breath
And the want
Of thought is death;

Then am I
A happy fly,
If I live,
Or if I die.

• poem by William Blake

Without mosquitoes many birds and bats (also both great pollinators) would die out :(