Autumn Revelations

Just this week, the leaves here began to turn in a marked way. And, finally, biology and urban naturalism are coming together. Leaves change color because of triggers such as length of light, temperature, and amount of precipitation, maybe things we already knew or could guess. But, what I learned is that these factors cause elements of the light-absorbing green pigment chlorophyll to degrade, allowing other pigments that were already present to show through. The stronger green now makes way for the orange and red (carotenoids) and yellow (xanthophylls), no longer masking the brilliant variety of color. 

Fruit Flies Revisited

I’m taking a biology class, which I believed would provide me with a wealth of information about the natural world and help me understand urban wildlife. Instead, I’m mired in the chemistry and physics of individual cells—electrons, ions, ATP, ADP, and etc.— which if I were less tired and thus more perceptive, I might be able to translate into acute and stunning observations about the world around me. I did read an interesting article related to biology in today’s New York Times science section about a scientist, Michael Dickinson, who studies fruit flies, those creatures about whom I was so flippant just two posts ago. As it turns out, fruit flies are one of the “most important laboratory animals in the history of biology, often used as a simple model for human genetics or neuroscience.” The article focused more, though, on how different the fruit fly is from us, for example, in its ability to fly and to taste with its wings. Although studied widely, Dickinson says, “we’re still fundamentally ignorant about the many features of its [the fruit fly’s] basic biology…” 

The Hummingbird Moth

During the last week or two acquaintances and friends have been exclaiming over the tiny hummingbird-like creatures they were seeing. When you first notice hummingbird moths, you really aren’t sure if they are hummingbirds or not. Their behavior and size can cause momentary confusion. They feed off of deep-lobed flowers, have a strong wing beat, and hover while feeding. A Calliope hummingbird measures 3.5 inches in length, whereas hummingbird moths can measure three inches or more in length. They are also called sphinx or hawk moths. We’re probably seeing what are named whitelined sphinx (Hyles lineata), with clear white lines marking their wings. Unlike other hornworms, which as moths fly at night, these are most active in late afternoon and dusk. Although the pupae are grossly impressive in size, shape, color, and texture, they are only pests and do not significantly damage plants. I don’t have a photo, but please look up a picture of a moth in flight and feeding on a flower—I think you’ll be impressed at how strongly they resemble hummingbirds.