You’ve probably seen them placidly buzzing around your garden in late spring. Maybe you mistook this solitary little insect for a fly.

Put away the swatter: They aren’t flies, they are bees — very helpful bees. Orchard mason bees (also called blue orchard bees, for their iridescent shine) are amazing pollinators and can dramatically increase fruit and berry yields in your backyard or orchard.

As their bigger cousins, the honeybees, struggle with mysterious hive collapse and environmental challenges, the tiny, gentle native bee is stepping up (or flying in).

While the bees are usually able to thrive on their own, many humans have started to help — to increase their numbers, improve fruit yields or just to watch them at work.

Attracting and observing mason bees is a great project to do with your kids. They don’t sting, and can easily be watched as they emerge from nests in the spring — especially if you hang a house with nesting tubes or nesting block. Kids can follow a female bee from the mud (that you’ve considerately supplied) to her nest, and learn how each bee uses pheromones to mark her personal nesting cavity, so she’ll always be able to find it.

What you need to support mason bees

1. A generous pollen source within 300 feet of your bee house.

2. A source of clay-based mud. In nature the female finds a small hole, usually in wood, lays an egg in it, then plugs it with mud. Note: They do NOT damage wood or create their own holes, they just use existing cracks and crevices.

3. A nesting place. You can let nature take its course or build simple nesting boxes by drilling a series of holes in a block of untreated wood (use a 5/16th-inch drill bit), from 3 to 5 inches deep. Or you can use a length of PVC pipe for a house, and fill it with paper or bamboo tubes (these come complete with bee cocoons at many garden centers in spring).

Hang the bee house on the south-facing side of a shed or building, where it has protection from wind and rain.

4. Most importantly, if you are going to attract mason bees, don’t use pesticides.

It’s important to clean or replace your nesting blocks, or to use new tubes every season, because of predatory mites and fungal diseases.

But if the prospect of caring for bees year-round is daunting, you can even rent them.

Bothell’s Rent Mason Bees (rentmasonbees.com) offers complete kits, ready to hang. For a small fee you can pick up bee cocoons and supplies in spring (you’ll be emailed with pickup times). After the bees have nested, you’ll be emailed that it’s time to return the bees. The folks at Rent Mason Bees clean the cocoons to remove any parasitic mites, chill them at the correct temperature and humidity for the winter, sterilize and repair the nest boxes and then let you know when and where you can pick up your bees in spring.

They are available at pickup sites all around Puget Sound.

Here’s an approximate schedule of mason bee activity:

March-April

If you’ve purchased bees at your garden center, put the tubes (which contain cocoons) out in a bee house hung in a south-facing, sheltered spot. Timing depends on the temperature, but a good guide is when your fruit trees are about 25 percent in bloom. Typically in Snohomish County, it’s mid-March.

Males will emerge first when it gets warm enough. They need to reach 80 degree to fly, but a sunny location for their house will warm them up enough even when it’s colder outside. They can be observed closely, as they are gentle and have no stinger.

Females emerge a few days or weeks later, depending on the weather. They start mating with males soon after. They can sting but are not aggressive and rarely do so unless frightened or squeezed.

Make sure you have a mud source (add clay if your soil is too sandy) near the bee house (not right under it). A shallow tray of water with stones for landing will encourage egg-laying.

Female bees lay a single egg at a time in the hole, and then add a ball of nectar and pollen — a food source for the larva. Then they plug the chamber with mud. They repeat the process for several days (one to two eggs a day) until the tube is full of eggs, each in a separate chamber with a pollen ball. The mason bee will lay the fertilized female eggs at the back of the hole and the males in the front — that’s why they emerge first.

May through late summer

Larva hatch within a few days of being laid and begin to eat the food in their chamber.

In about 10 days all the food is gone and the larva has the energy it needs to spin a cocoon and pupate in the chamber.

In mid to late June you can check that the tubes are capped with mud. That means they are filled with bee eggs.

By the end of June the eggs have all been laid and most of the females have died (kids, don’t be sad, that’s just how it works!). At that point, activity around the nest box really drops off.

Near the end of summer the bees in the nest transform into adults but stay in the cocoon. This is the safest time to move them.

By the end of August the larvae have become pupae inside the cocoons and are mature young bees. They stay dormant in this state until spring.

In late September, it’s safe to open the tubes to wash the cocoons, to remove mites. The mites are small and look like rust. Place cocoons into a paper bag or small cardboard box in an unheated garage or in a container with air holes in the refrigerator, until conditions are right for release in spring.

Humidity as well as temperature is important for the dormant bees, so if you decide to bring your bees in, check the sources below for more detailed instructions.

More information

WSU extension native bee information: bit.ly/1SlFSjY

www.sare.org/publications/bee/blue_orchard_bee.pdf

www.rentmasonbees.com