A randy time of year for those delicate aphids
Aphids, sexy? Just about the last thing I'd think has sex appeal would be aphids, those tiny, plant-sucking insects you only ever notice if they're on your roses. Often legless, wingless and almost translucent, they cluster on leaves and plant stems, push their needle-like mouthparts into a tender spot and suck out sap and nutrients.
Though aphids multiply in huge numbers all summer, every one you run into is a female. From the time they hatch from eggs in spring, in tree bark crevices where they overwinter, they reproduce parthenogenetically -- without males. I looked it up in the dictionary and found that "parthenos" means "virgin." So no wonder the Parthenon in Athens, that beautiful temple to the virgin goddess Athena, is graced with statues of females.
Back to aphids ... I was standing in Thickson's Woods, chatting with two students from Fleming College recently, when a small pale insect flew past. I stretched out my hand and it landed on my finger -- a tiny bit of white fluff with translucent wings.
"Look! Woolly aphid!" I exclaimed, and we all leaned close to examine it. The white filaments protruding like dandelion fluff from its abdomen are actually waxy threads that help insulate it both from heat and from cold, and provide camouflage.
I normally associate woolly aphids with alder thickets and butterfly counts midsummer. Larvae of harvesters, the only carnivorous butterflies in Canada, feed on woolly aphids, crawling along the stems where the cottony insects congregate. So what were woolly aphids doing flying around in a deciduous wood in November? A few days later I was out in the sugar bush and noticed a number flitting slowly about. Frost had already knocked back most insects, leaving the air clear, crisp and otherwise bug-free. What was going on with the woolly aphids? I was curious enough to dig out my insect books and look them up.
It turns out woolly aphids produce a couple of "winged" generations during the growing season, to transport the whole colony from one host plant species to another, and then back again. This particular type lives on maples in spring and fall, and alders in summer. Others utilize apple trees, beech, balsam, hawthorns, elm, pine and ash.
Just before winter, woolly alder aphids suddenly produce a generation of both males and females, with wings. They fly about and find each other, mate, and then the females lay eggs on the bark of maple trees, tucked away in protected crannies.
Such a complex, intricately orchestrated lifestyle they lead, so contrary to the spring mating frenzy of birds. How aphids know what works best for them, and when, is another one of those mysteries of nature. Just like what makes for sex appeal in a woolly aphid.
Nature queries: 905-725-2116 or mcarney@interlinks.net.
Durham resident Margaret Carney, in addition to writing nature-appreciation columns, has also published several children's books.