Last week, on Wednesday morning, I found myself sharing bathroom space with another creature. It seemed odd to be keeping company with a housefly in winter and for a moment, as I connected the presence of the fly with the small hole in the bathroom ceiling, I wondered what might be going on in the attic of my Eastport rental. I decided not to go there.

Towel in hand, it took all I could muster not to swat this creature against the wall. I have learned to live with spiders, rescuing them from certain drowning in the shower, and routinely return wayward stink bugs to the garden during the summer. Even wasps receive reprieve. But there is something sinister about a housefly, something carried forward from my youth when there was always a fly swatter, spotted with stains, hanging from a nail on the porch. A fly in our home was without hope.

During those few moments of struggle with baser instincts, I realized that I was experiencing what many people feel when they encounter aphids in the garden. There is no good in an aphid.

I have known otherwise rational gardeners that would bring out the big guns from the tool shed shelf when they spotted a single aphid on their roses. Some of the most toxic insecticides, including nicotine sulfate, malathion, diazinon and dimethoate have been used in the past to kill aphids, along with beneficial insects and other forms of garden life.

I would plead the case that a few aphids are evidence of a healthy garden ecosystem. Aphids have many predators, including ladybugs, lacewings, parasitic wasps and syrphid flies. Of course, to maintain populations of these beneficial insects, there needs to be a steady supply of aphids. If I see a few aphids in the garden along with numerous ladybugs, or lots of aphid exoskeletons punctured with the emergence holes of adult wasps, I feel that all is right with the world.

Entomologists who study aphids would agree with me that aphids rarely do enough damage to warrant intervention by the gardener. And in exceptional situations, when predators cannot keep up with a heavy infestation on young plants or your prize roses, mechanical controls will work. The gardener can dislodge them with a strong stream of water, or trap them with sticky yellow cards, thin plastic cards painted with Rustoleum Safety Yellow paint and Tanglefoot applied for stickiness.

Back to the fly; I overcame the urge to kill and left it alone, only to find it on the bathroom floor later in the day, dead of natural causes. There’s not much in a bathroom to keep a fly going.

A reader’s response to last week’s column: Kirby Ellis, of Ellis’ Greenhouse and Nursery in Hudson, e-mailed to let me know that finding Sungold and other favorite tomato transplants is not as difficult as I thought – I was just not looking in the right garden centers. He pointed out that local independent garden centers and nurseries are in competition with the big boxes and thus are much more customer-oriented, willing to carry small quantities of the newest vegetable varieties for their customers. The important thing is to let them know what we want!

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to reesermanley@shead.org. Include name, address and telephone number.