Blackhawk “Madame Butterfly” (1948) by Reed Crandall (plus Jack Cole)

Even though evolutionary biologists have long recognized the size discrepancy (sexual dimorphism) between male and female animals, they have struggled for decades to solve a major paradox: How can males and females of one species be of different sizes, given that they share the same genetic blueprints dictating their development and growth?

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To solve the problem researchers followed more than 1,200 caterpillars of the giant hawk moth (Manduca sexta) from the time they hatched, all the way through four molts and until they pupated.

Stillwell and Davidowitz discovered that female caterpillars initiate final larval stage a bit later than the males. By the time the female caterpillars pupate, they are larger, making for larger moths when they emerge.

So where is the advantage in being larger if you're a female insect?

"Biologists think selection favors large females because they can produce more offspring," Stillwell said. link

Modern Comics #78 (Oct. 1948); © DC Comics (probably).
Pencils by Reed Crandall; Inks by Chuck Cuidera

(Is it just me or do those henchmen look too much like they should be working for The Monarch from the Venture Bros. series?)

Ref.: A developmental perspective on the evolution of sexual size dimorphism of a moth. 2010. R. C.Stillwell and G, Davidowitz. Proc. Roy. Soc. B, published online before print on March 10.

Plus, from the same issue, a one-page gag strip by Jack Cole: