Naturewatch: Hoards of cluster flies and redpolls


Q: I know Naturewatch is now on The Eagle's Outdoors page, but this is an indoor question that I hope you can answer.

For the past week we have been getting big, fat house flies, mostly in sun-warmed windows, but also elsewhere in our house. What's the story?

A.J., Pittsfield

A: The location may have changed, but the format of this column remains the same: Answering "nature questions inside and outside the home."

The fly you are concerned with is not a house fly, but probably the cluster fly. Unlike the smaller common housefly (the most common indoor fly) that lives about two to three weeks, this species, for the last generation of the summer anyway, is long-lived, surviving up to seven months to over-winter (hibernate) inside homes and other buildings like barns, sheds, garages, office buildings, and factories.

Before we began building such diversified structures, they were content over-wintering in crevices of south-facing trees and rock outcrops.

I believe the fly is an alien like many of us, descending from European stock. While inside they will do no damage, and can be easily scooped up or otherwise captured for release or destruction.

Unlike the quick summer housefly, these slow, bumbling insects are not known to carry disease of any consequence to us. While housefly larvae, better known as maggots, feed upon garbage and feces, the cluster fly larvae feeds on earthworms.

Cluster flies, sometimes called attic flies, enter buildings in the autumn. And now that the weather is warming, they become anxious to get back to the fly's prime directive -- breeding. To this end, in attempting to find a way out, they become more obvious all of a sudden, and are often found on windowsills in clusters, hence the name.

Q: I have lived in the Town of Washington for eight years, and this is the first year I have had redpolls. They are here by the hundreds. They take over the feeders and no other birds can get in.

I have tried not feeding for a few days, then when I put the feeders out, they ALL come back.

I would like to see other birds that we have had in the past. Will they leave when the weather gets better or do I have them forever?

MARY, Washington

A: Even before this appears in print these "winter visitors" may already have begun their long journey home. If they are still dominating your feeder, keep in mind that these small finches, weighing slightly less than one-half ounce, will be flying about 1,000 miles to reach home!

According to Cornell Laboratory of Ornithology, "These small finches of the Arctic tundra and boreal forest migrate erratically, and they occasionally show up in large numbers as far south as the central U.S. During such irruption years, redpolls often congregate at bird feeders (particularly thistle or nyjer seed), allowing delightfully close looks."

Questions and comments for Thom Smith: Email


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