A bluebird box is wooden, with a 4-inch-by-5-inch bottom. To prevent it from becoming a lunch box for predators, it needs to be equipped with a predator guard and mounted on a pole. Tree- or fence-mounting makes eggs and chicks easy prey for snakes, raccoons, possums and squirrels.
There also needs to be some means of opening and closing a portion of the box - a pivoting side, a top you can unscrew - to allow for the weekly inspection. Be sure that this opening does not allow access to raccoons.
Bats are the main natural control of night-flying insects in the U.S., and they are protected in Maryland. Their appetite for mosquitoes, carriers of West Nile virus, is prodigious. One bat can eat up to 1,000 insects a night.
Bats love cloistered spaces where they can all crowd together like commuters on a Manhattan subway. That's why occupied bat condos look like furry sardine cans. The problem for many of us is when they start roosting in our attics.
"They normally roost in dead or dying trees," says Vezina. But in suburbs, where there aren't many dead or dying trees, the bats tend to seek refuge in homes, she says. "Bat houses give them a more appropriate place to live."
The Organization for Bat Conservation sells simple plans for building a bat house for $5. It also sells one- and three-tier bat condos for reasonable prices.
Indoors, you can create a composting worm bin, which will produce a bumper crop of worms along with fabulous compost. (The process is called vermiculture.). And you can do it in winter, without ever leaving the house. You can buy the worms or dig them up from your yard to get started.
"It's great in winter when you don't want to trudge out to the compost pile," says master gardener Susan Levi-Goerlich, who writes curriculum for Howard County schools.
Levi-Goerlich's worm bins, now 3 1/2 years old, consist of two 10-gallon Rubbermaid containers. She drilled air holes along the sides of one, which contains the worms and compost, and set it inside the un-aerated other, to catch the drainage. The aerated bin is then filled about 2/3 full with a bedding of shredded newspaper that has been soaked in water.
"I make it as wet as a wrung-out sponge," Levi-Goerlich says. "Then I bury food scraps and add worms."
There is virtually no smell. Levi-Goerlich harvests some worms and compost for her garden every three to four months. She keeps the rest of the worms and puts them back into the bin with fresh newspaper and starts all over again.
