Four photographs from Pittsburg show what the accompanying note said “my husband thought was a hummingbird nest” — something he picked off the ground from under a spruce tree in their yard.

“I don’t believe it is a nest made by hummers,” the wife wrote. “It has a divided section in the middle. Looks like it had two or four compartments. Any help in identifying this thing would be welcomed.”

Ruby-throated hummingbirds nest in a tree or shrub, frequently on a fork of a downward sloping twig. I’ve seen their nests saddled on a limb and have known them to nest in maple, birch, beech, hemlock and apple trees. They can build anywhere from five to 50 feet off the ground — usually 10 to 20 feet.

The nest — built by the female only — can be very difficult to see. It can appear as a small lichen-covered knot on the limb, about 11?2 inches high and an inch in diameter. Ruby-throats often return to the same location to nest year after year.

Other than an occasional rufous hummingbird, the ruby- throated is the only one of the 300 or so worldwide species of hummingbirds seen in New Hampshire.

The four photos included also showed a quarter to indicate the approximate size. As a result, the oblong nest appeared a bit larger than the usual nest constructed by a ruby-throated hummingbird.

Other than the general size and shape, this nest had two other abnormalities that did not fit an average hummingbird.

First, the outside of every ruby-throat’s nest I’ve seen has been covered with lichens held in place by cobwebs. In addition to having no lichens, only one half of this structure was covered with a finely woven net has small apertures, not unlike that of a commercial hair net.

Second was the divided section in the middle. Generally, hummingbirds lay only two eggs and that raises this question: How could she brood two eggs at a time if each was laid in a separate compartment?

One last point was distinctly bag-shaped, very much smaller, but similar to the hanging nest of a Baltimore oriole. There was no indication of its having been attached to a tree limb or even between the crotch of two limbs as a hummingbird would do.

If I had to guess, I believe this item could have been constructed by a caterpillar as a cocoon for a moth or butterfly to complete its development. Perhaps other readers can help solve this mystery.

Don't make hummingbird formula too strong

Recently, I’ve read and heard reports of folks using a much stronger recipe for filling their hummingbird feeders than is generally recommended. Some have mixed a half-cup of sugar to a cup of water. This strength is not a good idea, because, when used for a long period of time, can be harmful to hummingbirds.

The following formula is recommended: Use one cup of granulated white sugar for each four cups of water. Bring the solution to a full boil and then turn off the heat. Boiling too long will concentrate the sugar beyond the desirable range. Clean and refill your feeder every three or four days to prevent any danger from mold.

Do not substitute other sweeteners for granulated sugar. Powdered sugar, for example, contains corn starch that can contribute to early fermentation. Brown sugar contains iron and can be deadly following lengthy feeding. Substituting honey for sugar is particularly dangerous in that it may produce fungus infections and may also contain certain botulism toxins. And artificial sweeteners are not advised. Plan to leave hummingbird feeders out quite late in the fall to help migrating birds on their way.

In addition to artificial feeding of hummingbirds there are several nectar producing flowers that attract these delightful birds. They particularly appreciate bright red, pink and orange tubular flowers such as geraniums and petunias. Others that attract hummingbirds include bee balm, impatiens, salvia, columbine, day-lilies, morning glories, fuchsia, and trumpet vines.

Stacey Cole’s address is 529 W. Swanzey Road, Swanzey 03446.