C R E A T U R E   C O M F O R T S

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An Agave Stalk Becomes a Nursery

by Sue Hakala,
Master Gardener

Oh dear! Your treasured agave has sent up its life-ending flower stalk. Typical of its genus, you will have a chance to enjoy its superbly beautiful blooms for a period of time, and then it will die. The value of your agave needn't end there, however. By converting the stalk into a nursery, you can preserve it as a reminder of your special plant.

To do this, cut the stalk to an appealing size with a saw and then wedge it between heavy rocks or similar features to maintain its verticality. The best location is a protected, semi-shaded area. As the stalk dries out it will become the perfect nursery for carpenter bees. These handsome bees are hairy, bluish-black, about an inch long, and as wide as your thumb. They won't sting you unless trapped or threatened, and they are solitary and do not form a hive. They are excellent pollinators, and therefore valuable additions to your landscape.

Single female carpenter bees nest in wood. They will compete heavily for a chance to nest in your stalk. In the spring, you can sit at a safe distance of about ten feet and observe the females posturing with each other to see who will get the prize, sometimes for days at a time.

The winning architect will chew into the stalk to tunnel out an 8- to 9-inch section of tunnel that is three-quarters of an inch in diameter. If you listen closely you'll be able to hear the chewing and digging, and you'll notice telltale sawdust collecting at the base of the stalk. At some point during this time the bee will mate, and when her tunnel is finished she will collect pollen-fertilizing your plants in the process-and return to the nest with it.

The female carpenter bee will then roll the pollen into a ball and place in the bottom of the tunnel to become food for her developing offspring, after which she will lay an egg on top. Finally, she will chew cellulose from the stalk and form a roof over the cell. She will continue this process until the tunnel is relatively full of eggs.

I've observed females returning to their tunnel at sunset for their night's sleep, and then very early the next morning I've seen them sleeping in the tunnel doorway guarding their brood. When the bees are ready to emerge, each in turn will chew through the roof of their cell. They bees will then over-winter in the tunnels; in this case inside the agave stalk you have provided.

Carpenter bees normally use dead tree limbs or other unfinished wood such as firewood as nurseries. If you see them tunneling into wood that has value to you, you can protect it by covering it, varnishing it or painting it.

I've had bees nesting in a cherished agave stalk for several years. They provide pollination as well as a great deal of entertainment. Even better, observing them affords children a wonderful lesson in natural history.

Maricopa County Master Gardener Volunteer Information
Last Updated January 23, 2004
Author: Lucy K. Bradley, Extension Agent Urban Horticulture, University of Arizona Cooperative Extension, Maricopa County
© 1997 The University of Arizona, College of Agriculture and Life Sciences, Cooperative Extension in Maricopa County
Comments to Maricopa-hort@ag.arizona.edu 4341 E. Broadway Road, Phoenix, AZ 85040,
Voice: (602) 470-8086 ext. 301, Fax (602) 470-8092