In case anyone is wondering if our insect hotel is working, I have proof! If you look at the bamboo on the lower right, you can see that several of the holes have been covered with green pieces of leaves (Fig.1). This is the work of leaf-cutter bees (Fig.2). In July, a friend found me a mini-insect hotel that was going for cheap at Aldi’s — you know something is getting trendy when Aldi’s starts selling it. Anyway, while it didn’t have quite the flair of the one my beloved made for me, I thought why not? Well as you can see several of the holes have been sealed with mud by mason bees (Figs. 3 and 4).
Figure 1. Brood chambers of leaf-cutter bees.
Mason bees and leaf-cutter bees are represented by several species in the family Megachilidae. Most of the bees in this family are solitary bees meaning that each female performs all her own tasks, unlike the division of labor in a honey bee colony. She collects pollen on fine hairs on the underneath of her abdomen (this pollen spreads easily to the next flower making them excellent pollinators), then finds an appropriate tube to lay an egg in, while provisioning it with pollen for when her hungry larva hatches.
Figure 2. Common species of leaf-cutter bee (USDA ARS free image).
She then seals that part of the tube with either a piece of leaf or mud, depending on the species, and goes looking for more pollen to repeat the process until all the space in that tube is filled. Whew, sounds exhausting! Which is why these small, gentle bees don’t waste their time defending their brood like honey bees. The only way you’ll get stung by one of these is if you grab it.
Figure 3. Brood chambers of Mason bees.
Now here’s where it gets really interesting — at least to me. I went out to look at our homemade insect hotel and found that a new, different species has recently been using some of the tubes and stuffing the openings with grass (Fig. 5). I did a little research and found out there are several species of “grass-carrying” wasps in the family Sphecidae that also use these tubes for their brood. These wasps aren’t as good at pollinating as our solitary bees, but I’m a big fan of diversity and isn’t that grass cute? I’m hoping to catch one in the act.
Figure 4. Species of Mason bee (USDA ARS free image).
Figure 5. Brood chambers for “grass-carrying” wasps.
I think the take home point of this whole endeavor is highlighted by the fact that we live just a couple of blocks from the massive Brookside student apartment complex. Can sweet little pollinators thrive so close to all that concrete and trash? Apparently, yes. You can live downtown and still help nature. In fact, recent research indicates higher abundance and diversity of native bees in urban areas where there are higher densities of flowers and less pesticide use than fields in rural areas (D.M. Hall, et al. 2017. The City as a Refuge for Insect Pollinators. Conservation Biology 31:24-29.)
So, no more excuses! Start doing your part! Why not put a few native plants along the border of your veggie garden? If you don’t want a perennial, then plant a few annual sunflowers or zinnias. Both are good nectar sources for many insects and make lovely bouquets. For more information on helping these pollinators while producing nourishing food for yourself and friends, take a look at this website:
The Honeybee Conservancy