The Wonders of Instinct: Chapters in the Psychology of Insects — A Closer Reading

The Burying-Beetles' Problem-Solving

In the chapters on burying-beetles (Necrophori), Fabre designs experiments that test the limits of instinct. He fixes a mole to a horizontal crossbar, ties a mouse to a thyme bush, and plants a stake with a mole attached by its hind feet. The beetles must dig, tug, or gnaw bonds to retrieve the carcass. Fabre records their successes and failures with the precision of a lab notebook: in Experiment 4, when the stake is slanted and the mole touches ground two inches from the base, the beetles dig uselessly under the body and never try to overturn the stake. They eventually succeed only by gnawing the bond—their 'usual method.' These experiments reveal a pattern: the beetles are not mindless automata but creatures whose instinctual repertoire includes flexible tactics, yet they can be stumped by a simple geometric change. Fabre does not anthropomorphize; he simply documents what they do and fail to do.

The Spider's Web as Inscribed Signature

Fabre's description of the Banded Epeira's web-building is strikingly aesthetic. After finishing her web, the spider 'inscribes her flourish'—a distinctive, patterned addition that Fabre treats as a kind of signature. The phrase captures his attention to individual variation within species. He also observes the spider letting herself drop by the end of her thread and swathing her capture, noting that the web 'has given way in many places during the struggle.' These details accumulate into a portrait of behavior that is both stereotyped and responsive to circumstance. Fabre does not claim the spider is conscious, but he refuses to reduce her actions to mere reflex. The web is not just a trap; it is an artifact shaped by the spider's particular movements, and Fabre reads it as one might read a manuscript.

The Energy Puzzle of the Fasting Spiderlings

Returning to the young Lycosae, Fabre deepens his inquiry into the nature of animal energy. He calculates that the egg supplies the materials for the tiny frames, and since the spiderlings do not grow, they need no additional plastic food. Yet they remain 'splendidly nimble and spirited,' able to scramble up a leg and hang on to their neighbours. Fabre rejects the idea that they can live on nothing. He draws an analogy to the locomotive: coal provides heat transformed into action. For animals, that coal is food, which ultimately stores solar energy. But the spiderlings take no food. Fabre then asks whether solar energy might enter them directly, 'without being served up through the intermediary of food.' He leaves the question open, acknowledging that chemical science may one day provide synthetic foodstuffs, but for now the puzzle stands as a challenge to conventional physiology.

Readers should approach The Wonders of Instinct as a series of experimental reports rather than a systematic treatise. Fabre's strength lies in his willingness to let a single anomalous observation—a spiderling that moves without eating, a beetle that fails to dig in the right spot—unsettle received ideas. The book rewards those who read slowly, attending to the precise conditions of each experiment and the tentative conclusions Fabre draws. His voice is that of a naturalist who trusts his eyes more than his theories.

That rainy afternoon, I lingered over Fabre’s burying-beetles, their grim, fixed rituals—until one deviated, improvising. It made me wonder how much of what we call instinct is really just habit under pressure. Later, I found myself glancing through Our Common Insects A Popular Account of the Insects of Our Fields, Forests, Gardens and Houses — Key Ideas to Explore, and the same quiet curiosity followed me from page to page.