By Executive Director Nancy L.C. Steele

When we bought our new house near Cottonwood, the sellers left us a few things, as sellers do. They left us some ant poison, because they couldn’t imagine that we wouldn’t want to poison the ants (we didn’t). They left us some furniture, some we wanted, some we didn’t. And they left us some random things in the back, like dog toys (we don’t have dogs) and a carved stick. 

Once I bought some patio furniture, I settled onto the porch with my binoculars for some good birdwatching. I was attracted to the house by the large back porch overlooking a garden, along with the large expanse of native trees and shrubs. 

Tidying up, I leaned the 3 ft high carved stick against the wall of the house next to my chair. The stick was a soft wood, likely sycamore. It had a few round holes in it, and I had an idea what the holes were from. Sure enough, soon a great big black carpenter bee flew straight towards the stick. I wasn’t worried; she had no interest in me. She was a Xylocopa sonorina, a valley carpenter bee. She was building nests for her babies in the holes in the stick. 

I am fascinated by our native solitary bees, especially carpenter bees, cactus bees, leafcutter bees, and sweat bees. This last summer I paid attention to a tiny bee that was iridescent green with stripes on its abdomen. I found them in my bathroom but also on a flower called the yellow or golden beeplant. The tiny bee, I found out, was a honey-tailed striped sweat bee. They also nest in holes like carpenter bees, albeit very tiny ones in plant stems. 

Over the summer, I was thrilled to be able to watch queen carpenter bees busily creating their nests. Carpenter bee females use their powerful jaws to excavate tunnels in wood or woody stems. Each bee collect pollen and kneads it into a tiny loaf, using her saliva and flower nectar. She places the loaf of bee bread of pollen at the bottom of the nest and lays her egg on top. She has given her baby all the food it will need to develop from an egg to adult. 

Her next step is to wall in her baby. She chews up some wood, creating a natural particle board. She calculates how big of a nest her offspring will need to develop into an adult. Then she builds a small partition and starts over to create a space for her next baby. 

When you think about it, this is pretty complex behavior! 

The bee mother does not take care of her babies after she lays the egg, but she leaves them with everything they need to grow up. For after she finishes her nests, she dies. Her babies develop, growing from egg to larva to pupa and adult. Whether the bees are pupae or adults, they stay in the nest, overwintering until spring, when they complete their development and emerge from their tunnels.

You probably want to know how you can keep carpenter bees from building those tunnels, which are often excavated in the wood of your house. Carpenter bees don’t like to bore tunnels in painted or stained wood, so that is the first step. Paint or stain wood if you don’t want holes drilled into it. From experience, I know that the larger problem is the woodpeckers that enlarge the tunnels in their efforts to eat the tasty baby carpenter bees. Keeping up with maintenance, filling holes, and painting wood will help. 

Carpenter bees are native bees and I hope that you will give them a chance to survive. They prefer to nest in the wood of trees like sycamores and mesquite, and stems like yucca and agave. If you leave out dead limbs or pieces of tree trunk, they will be less likely to bother your house. 

Carpenter bees, like almost all bees, are pollinators. While everyone knows about the role of honeybees in pollination, you may not know that native bees are better than honeybees at pollinating native flowers. Native bees were here long before honeybees were brought to this continent. Arizona alone has around 1,600 different types of native bees, each of them specialists in pollinating a small number of flowers. 

I’ve run out of space to tell you more about our native bees, so I’ll have to continue this subject in another month. If you want to encourage native bees, leave parts of your garden wild and a little messy. Some bees nest underground and need bare soil. Others nest in plant stems and will appreciate it if you leave shrubs alone. Some hide under leaves during the winter. Leave space for bees and you’ll be rewarded with flowers and fruits.

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