From an Entomologist’s Backyard

Happenings in a Monkey Flower

An unfertilized flower (left) has an open, mouthlike stigma—the pollen-receiving tip of the flower’s pistil (the female part). The stigma’s lower lip closes when stimulated (right), either permanently if the flower has been pollinated, or temporarily if it hasn’t. A temporary closure can be caused by touching the lower lip with a toothpick or twig. Photo by Edward S. Ross.

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Jul-Sep 2005

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by Edward S. Ross — published July 01, 2006

A walk with Edward Ross, curator emeritus of entomology at the California Academy of Sciences, around his Mill Valley home is an invitation into a fascinating, miniaturized world. Here, the seemingly choreographed bits of chance and intention that make up a healthy ecosystem are revealed in the blooms of the sticky monkey flower (Mimulus aurantiacus) and its varied insect visitors. Here, we show just a few of the many such interactions that Ross has captured on film over 58 years at his hillside retreat.

--Dan Rademacher

The sticky monkey flower is part of a group of shrublike Mimulus species adapted to drier climates. The rather rigid leaves exude sticky phenolic resin, which repels most would-be foliage eaters. Larvae of the chalcedon, or variable, checkerspot butterfly (Euphydryas chalcedona) are an exception. But as the season heats up, even they can no longer eat the increasingly toxic leaves. On cool days and nights, on the other hand, spiderflies may use the flower's corolla as a "sleeping bag" With the fly immobilized by cold, one can tear away part of the corolla to see the "sleeper" within.

The chalcedon checkerspot is a common butterfly that, in Mill Valley, stays close to the habitat of it larvae's favorite food, the sticky monkey flower. (In some areas, larvae occasionally feed on California plantain.) In early spring, the butterfly lays its eggs on the underside of a monkey flower leaf.