an inordinate fondness

The story, often repeated with variations, concerns a conversation between a cleric and population geneticist J.B.S. Haldane. The cleric asked Haldane what he could infer about the creator from observing the natural world. Haldane supposedly replied that the creator had “an inordinate fondness for beetles”.

The garden certainly supports this observation. The diversity of beetles I find while merely walking or watering is amazing. But getting a little closer to the ground while weeding often disturbs some remarkable beetles one would not see otherwise. My most recent discovery was a metallic green-gold beetle, about ¼ inch. The color was quite vivid but when I looked at it later it was red-orange with three black spots on each wing. I keyed it to the family Chrysomelidae, subfamily Cassidinae. These are the tortoise beetles, the name owing to the tortoise shell shape. But the color change became more puzzling. When I looked at the beetle the next morning I was surprised to see the metallic coloring again. Numerous Google word combinations later I happened upon a Texas A&M page describing the golden tortoise beetle, Charidotella sexpunctata bicolor (Fabricius) (= Metriona bicolor (Fabricius)). The metallic coloring of this beetle disappears when disturbed. This phenomenon is described in more detail in an article originally appearing in Scarabogram, Sept. 1994, New Series No. 173, pp. 2-3:

The gold color is caused by a thin layer of moisture between the cuticle and an inner layer of the elytra. Apparently the insect is able to "voluntarily" squeeze this layer, reducing its thickness and eliminating the gold color. This change also occurs involuntarily when the beetle is under moisture stress, and, of course, when it dies.

This moisture reflects light, resulting in the appearance of metallic gold, and illustrates the structural coloring responsible for much of the iridescence observed in insects.

When I first came across Haldane’s quote many years ago I presumed he was referring to the sheer numbers of beetles in the world. Coleoptera is the largest order of insects with a quarter of a million species worldwide, 30,000 in North America. These numbers could certainly have prompted the comment. But after studying the beetles and observing my own local representatives I think it more likely that Haldane saw the enormous complexity and diversity of the beetles as an apt expression of “an inordinate fondness”.