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The Smooth Operator

A study in hot-to-trot moth mating habits



Over the last few weeks, several readers called, sent emails and text messages, asking about some moths that have been emerging. They all wanted to know: "What is this thing?" You have to admit, coming upon that beauty at night, fluttering about the porch light, or in the morning clinging to the light or on the side of the house or barn will positively get your attention.

This beautiful creature is a common resident of this neck-of-the-woods, the ceanothus silk moth, but it usually doesn't comes to people's attention until late May and early June. Its early emergence is a phenomena that just adds more fuel to the claims of climate change. An unusually warm, dry winter provides better than normal conditions for the pupae of the moths to develop, and tends to speed up metamorphosis.

When I was living with Dean and Lily Hollinshead at Timberlane Ranch, which is now Bend Park and Rec's community farm on Jones Road, almost every spring in late May and June I'd find adult ceanothus moths perched on the side of the barn and milk pallor in the morning, and Lily's darn barn cats trying to catch them.

Named for the principal plant the larvae feed on, ceanothus velutinus, the moth goes as far north as British Columbia, east to Colorado, and south to Sacramento. The larva (caterpillars) also feed on California buckthorn, choke cheery, manzanita, alder, birch, hazel, saxifragaceae, douglas fir, and willow. Unlike most moths, the adults don't eat anything; they mate and die.

The eggs are laid in mid-summer, after mating has taken place, the female is gravid, and when they're in the best of health. Egg-laying is usually accomplished at night, when the female flies from food plant to food plant, depositing five or six eggs in a row on the underside of the leaf. The adults die after they have accomplished this vital part of life.

The caterpillar grows rapidly, going from instar to instar as it increases in size. When it reaches size and age to pupate, the caterpillar builds a silken case inside an outer silken case, leaves it suspended in the branches of the food shrub or tree, and the miracle of metamorphosis begins.

For the hair-splitters, the ceanothus silk moth (hyalophora euryalus) is in the family saturniidae. It is found in the dry intermontane valleys and interior of the Northwest, all the way from Prince George Sound to as far south as Baja California.

They're a big moth with a wingspan of 3.5 to 5 inches, and they're on the wing from January to July, depending on the geographical location. One of the most alluring parts of the ceanothus silk moth is the method by which the male and female get together.

The males find the females with the use of their huge feathery antennae. Sex pheromones (perfume if you will) emitted by the female moth drift through the night air and the male moth, after one whiff of that delightful scent, can't help himself; he's a goner.

As a youngster living on my grandfather's farm in Connecticut, I discovered what happens when a male moth senses a female's pheromone. It was late at night, my uncles and I were fast asleep when I was awakened by a constant "thumping" against the window of our upstairs bedroom. I was the youngest, so I was kicked out of bend to see what it was all about, grabbed up the flashlight we always kept on the night stand, and crept up to the window.

There, bold as brass, was the eastern counterpart of our ceanothus, the cecropia moth, bumping against the window. My Uncle Harry and my Uncle Horace seemed to have no understanding for this behavior, so I woke up my Uncle Ben, who started me going on the naturalist trail I'm on today.

When I explained what I found, he jumped out of bed and exclaimed, "I don't believe it," and ran into the bedroom we were sleeping in. Without hesitating, he went to a big bureau, opened the top draw, took out a cigar box and when he opened it, out flew a cecropia moth.

He was so excited he couldn't speak for a moment, then with his scientific head working, he explained what was going on: "Look at that, will you!" he began. "See? That's a female cecropia, the moth outside is a male, and he's sensing this female's perfume that is coming out of the cigar box, out of the bureau, and out of the house."

Then to prove his point, he opened the window to allow the moths to meet, and the male made a beeline right to her. The last I saw of them was when Uncle Ben caught them in his butterfly net, and taking them to the opened window, released them into the night.

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