Gardening: Native bee species more effective
We’ve gotten through the holiday season and I’m beginning to hear people talk about spring. While the warmer weather is still a ways off, it is time to think about installing nesting boxes for some of our native bees.
Several hundred native bees in the Northwest were here long before the honeybee came west with the pioneers. The two most common ones are the blue orchard mason bee and the alfalfa or leafcutter bee.
Most of our native bees are solitary – they don’t create a hive like honeybees but build nests in cavities in old wooden buildings, trees or in the ground. Because they don’t have a nest to defend, they are very docile and rarely sting.
These bees are much more efficient pollinators than honeybees. The leafcutter bee is 15 times more effective, and 250 mason bees will pollinate as much as a 10,000-bee hive. The reason? They are smaller than a honeybee and able to get into smaller flowers.
The blue orchard mason bee comes out in late March and pollinates through the spring before laying new larvae and disappearing from the garden by early June. The larvae are placed in holes in wood and the hole capped with mud, hence, the name.
The leafcutter bee comes out at the end of May and pollinates summer crops before nesting in August for the year. It also lays its larvae in holes but builds its nest out of perfect half circles of leaves. Don’t get too happy with the pesticides when you see leaves with round holes cut out of them.
To attract these bees to your garden, first plant bee friendly plants that bloom from early spring well into the summer. Next, gather pithy or hollow stems of bamboo, Japanese knotweed, elderberry, sunflower or raspberry. Cut them about 6 inches long and bundle them together. Holes can also be drilled into old logs or blocks of untreated wood to make cavities. Drill multiple 7/16-inch holes 6 inches deep. Place the nesting materials in a sheltered but sunny place or in a wood box with a roof mounted on a fence facing south into the sun. Cardboard nesting tubes can also be purchased online and packed into a roofed wooden box facing the sun.
If you are in a hurry to have the bees, you can purchase mason bees online from several sources. Some will come as bare cocoons, and others will come as straws with larvae inside. Personally, I like those that come in a straw because they are easier to handle, and they have some protection for the weather and predators. I started with six straws in 2012, and my colony now has several hundred bees.
For care, the bees only need fresh nesting materials each year. I clean out my cardboard tubes in late January and put new paper straws in the box, so it is ready when the mason bees come out in late March.