On New Year's Day 1917, Robert Frost wrote to his friend Louis Untermeyer:

Frost's poem ‘The White-Tailed Hornet’ (1936), which is subtitled ‘or, The Revision of Theories’, appears to do precisely this. Observing the behaviour of a nearby hornet as it pursues a fly, the speaker prepares to marvel at the creature's powers of instinct:

Frost is alluding to Fabre's account of the paralysing precision of the hairy sand wasp which, as we saw in the preceding chapter, was cited by Bergson to illustrate his theory of instinct as ‘nowhere so developed as in the insect world’. Initially, the behaviour of the hornet seems to confirm this view. But something goes wrong:

By mistaking a nailhead for a fly, the hornet exhibits a curiously imprecise mode of behaviour that ‘won't quite formulate’ to Bergson and Fabre's theories, prompting the speaker to ask: ‘Won't this whole instinct matter bear revision?’

Frost's fascination with insect behaviour was long-standing: from early poems such as ‘A Prayer in Spring’ (1915) to later verses – ‘A Considerable Speck’ (1939), ‘Pod of the Milkweed’ (1954) – the author details his observations of ants, mites, wasps, butterflies and moths. In ‘The White-Tailed Hornet’, however, the sense of admiration that runs through many of Frost's insect poems is replaced by a tone of deflation. No longer capable of arresting the human onlooker in a state of awe, the creature misses its mark; rather than hitting on the poet's ‘sneeze-nerve’, what it strikes is ‘just a nailhead’.