When I announced that I was looking at bee boxes for the new Pollinator Garden (see October 2015 print issue of Newsletter for Members), everyone looked at me like I was a crazy lady thinking I meant to install honeybee hives in the middle of what will hopefully be a popular trail. Most people harbor an unnatural fear of bees, not unusual given the number of reports about Africanized bee attacks. But nature has blessed Arizona with well over 1000 species of native bees, all dependent on flower nectar and pollen, most of which nest in the ground, in hollow stems, old beetle tunnels or in cracks and crevices. Unlike honeybees, our native bees are mostly solitary and do not form colonies.
For our new Pollinator Garden, we chose to purchase a couple of sculptural bee habitats, garden art with holes drilled into them, created by Tucson artist Greg Corman. You can also create your own bee habitats at home with hollow tubes of some sort, such as bamboo, or by drilling holes into dead branches or snags. The bees that inhabit them are hole-nesters – mason bees, resin bees, and leafcutter bees. These bees will look for already existing holes, usually tunnels made by beetles into logs or old snags.
So, what’s going on inside these tunnels? The females line the holes with mud or leaves, constructing horizontal brood cells that are generally lined up end-to-end in any given drilled hole. Each cell will contain one egg and will be individually stocked with all the food required for the larva as it becomes an adult. As each cell chamber is completed, the female will create a partition made from mud or leaves. The final plug will be thicker, meant to keep out moisture and parasites. The leafcutter bees are the culprits responsible for creating all the circular lacy cutouts on your perfect leaves during the summer, which are then used to line the nests. The mature larvae over-winter in their cells, emerging as adults in the spring. Newly emerged females will then begin constructing nests, and the cycle begins all over again.
Another bee worth providing nesting materials for is the carpenter bee. Generally referred to as “robust,” it is a large bee that delights in frightening the unsuspecting by flying very close to a person’s head and loudly buzzing its presence. The males have no stingers but the females do, although while big, black and scary, they are harmless when left alone. They love agave stalks, bamboo stems and pieces of wood, especially those that are the backbone for hanging wind chimes and mobiles. As their name implies, they chew perfectly round holes into the wood for their nesting burrows. (My sister and I caught one once in a butterfly net and watched, incredulous, as it chewed itself out in seconds flat.) Much like the leafcutter bees, the carpenter bees will provide a food ball onto which they lay an egg, creating several identical chambers that are partitioned off from each other.
Arizona’s native bees are important pollinators of our desert plants and are generally much more efficient at it than the non-native honeybee. Native bees rarely sting and if they do, it tends to be pretty mild. They are worth inviting into your garden and are fun to watch. Instructions for building bee habitats abound on the Internet.