The Size of Butterflies

Cabbage White Butterflies

Cabbage White Butterflies

Larger sized butterflies can lay more eggs than smaller ones. In one study*, the size of wild collected cabbage white butterflies varied 3X, from 80 mg to 240 mg. Since smaller butterflies lay fewer eggs, why does the size of these butterflies not increase over time?

There are several competing factors in the equation. Not all variation in size is genetic. Some is nutritional. Caterpillars that develop on less nutritious resources or exhaust their food supply may pupate at a smaller weight which ensures some offspring (instead of zero). Smaller individuals may be able to exploit resources of marginal size that are too small to support larger individuals. Smaller individuals may develop more rapidly and in some conditions, have an additional generation. If there is a 20% difference in fecundity between the largest and smallest individual, that 20% could be greatly exceeded by an additional generation.

*N. Gilbert. Control of Fecundity in Pieris rapae: I. The Problem. Journal of Animal Ecology, Vol. 53, No. 2 (Jun., 1984), pp. 581-588.
http://www.jstor.org/stable/4536

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
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One Response to The Size of Butterflies

  1. The biggest butterfly species in the world is a “Birdwing”. This creature is from the Solomon Islands and its wings span 30 cm. It’s amazing…Don’t you think so?

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