A leafcutter bee visits my garden.
On a warm, sunny day in late spring last year, I discovered that I had inadvertently built a condo for one of our precious native pollinators. Some years earlier, he had piled a pile of twigs and small branches against the south side of the house to use as firewood. Well, it had been a few years since we had lit a fire in the fireplace, and in the meantime, dozens of little bees had found a home. The shiny black bees burrowed into the smallest cracks and holes in the twigs. After some research, I determined that they were small carpenter bees of the genus ceratin. They were mothers who provisioned their nests.
About 30 percent of North America’s 4,000 bee species nest above ground, in twigs, stems, old beetle burrows in wood or other narrow crevices. These friendly, non-aggressive bees create small brood rooms within the stems. They create partitions with various materials; For example, small carpenter bees use pith and their own saliva, mason bees use mud, and leafcutter bees use pieces of leaves or petals. The mother places a ball of pollen mixed with nectar in each cell and deposits an egg on it. The larvae will develop with the food left for them by their mother, they will spend the winter as a pupa inside the stem and emerge the following year as adults to begin the cycle again.
If you want more of these critters in your garden, why wouldn’t you? They are excellent pollinators and a pleasure to watch! There are some things you can do. Firstly, obviously, it can provide nesting opportunities. Bundles of hollow or pithy stems placed in sunny, dry locations around your garden will attract them. Heather Holmauthor of several excellent books on pollinators, including Native plant pollinatorsBee condos like mine are unintentionally not a great idea. Massive adaptations encourage predation and disease. It is best to distribute housing opportunities around the garden. The best thing to do, Holm says, is to leave about 15 inches of stem standing in the spring when you cut your perennials, and leave them standing. Bees will lay eggs on the stems that season, the young will overwinter inside and emerge the following year. It may seem a little fiddly to leave the dead stems, but the new growth will cover them in no time. Additionally, you will only need to do this with the most suitable, strong-stemmed plants, such as asters, perennial sunflowers, and switchgrass.
To attract cavity-nesting bees, you can also drill holes in logs. do You have logs on your property, right? They are wonderful for wildlife! Holes about 1/4 to 3/8 inch wide and six inches deep are excellent for mason bees. A variety of other sized holes (less than 1/2 inch in diameter) may attract additional species. These cavities can also attract solitary wasps, which are also not aggressive and are a joy to have in the garden. They feed on caterpillars, crickets, aphids and other insects.
Also be sure to provide building materials for your mother bees. Mason bees will need a source of mud to build their brood cells. Leafcutter bees, depending on where you live, prefer to use certain leaves to make their homes, such as rose, lilac, or redbud. Some use petals like those of Enotera. In our area, a leafcutter species loves clarkia petals, so be sure to include this beautiful native wildflower in your plantings if you live in the Northwest.
Last but not least, you will want to provide your bees with abundant sources of nectar and pollen during the growing season. Many of our smaller native bees have very limited foraging areas. They cannot travel miles like bees or bumblebees. It is likely that my ceratin bees, for example, never leave my garden. I make sure they always have plenty to choose from. Native plants are generally best. I’ve had good luck with natives and near-natives like Limnanthes, Ceanothus, SidalceaCalifornia poppies, penstemons, sunflowers, gum (Grindelia), aster, goldenrod and eternal pearl. I will continue to try others to see what the native bees like best. I can’t wait for another season! I can’t wait to find out who will visit me, who will stay for lunch, and who will make a home.
