Guest Post: If You Build It, They Will Come

Our California backyard used to be a flat, denuded expanse of hard‐packed soil surrounding a single tree. We started growing things there a few years ago, and managed to build a biodiverse backyard menagerie. But it took a while. In the first year, any flowers or vegetables we planted were plagued by pill bugs, earwigs and aphids — probably because there was nothing else for them to eat. All the other plants that successfully took hold in the soil were sometimes stunted or susceptible to diseases like powdery mildew. We thought we were doing everything right, but we were pretty sure something was missing in the big picture.

Year by year, we improved the soil by composting all our kitchen scraps and yard trimmings and adding them back into the soil, and by also planting flowers and shrubs that attract all kinds of small animals. After a few years, we noticed a big change: our back yard was turning into a garden. We knew something was different when we heard our first katydids stridulating (shrill chirping) one summer. It seemed like we were the only ones on the block who had them. Soon we were hearing crickets from late summer through late fall, and even into early California winter. Compare to what that same bare patch of ground looked like this spring (right).

We think that this major change can be explained one word: diversity. It isn’t just about planting a bunch of stuff, but rather letting all the growth and change cycle through several seasons, to some kind of equilibrium. By enriching the soil and encouraging many different kinds of plants, we made something of habitat that became increasingly complex over time. We watched it become a type of oasis within a suburban block of groomed monoculture lawns and overly‐trimmed juniper hedges.

But here’s the fun part. With so many different plants, many different types of insects came to visit. We were happy to see more butterflies and fewer earwigs (although we have come to admire the earwigs now!). And as the soil improved, the plants seemed stronger and less prone to disease like mildew and general rot. Things seemed more in balance, with each organism exchanging with another, and all was thriving.

Then the birds came. We think it’s because of the diversity of plants and insects that many different kinds of birds started to appear. Maybe it was the colors too. This prompted us to buy a field guide to birds and finally learn something about them. We also noticed a boom in our spider population. Now, every autumn, we have our very own local population of big, fat orb‐weavers who spin picture‐perfect webs the size of dinner plates, all over the garden. Spiders eat insects (and other spiders), and birds eat spiders, so it seems all of a piece.

But one of the most exciting things that happened was the bees came. We noticed the honeybees first because there were so many (two of our neighbors keep honeybee hives in their yards). But on closer inspection we began to see lots of other different little bees and wasps. So we started to do some research on all the different kinds of bees. Turns out, most of the bees we see don't sting at all, and we identified most of them as native to the area — they have been here for thousands of years. Many of them are solitary (non‐hive‐dwelling) species.

Some of the bees are metallic blue and iridescent green, and one type looks like a cross between a tiny fly and a bee, with an orange abdomen. The most prevalent natives are carpenter bees, orchard‐mason bees, ground‐dwelling bumblebees, and leafcutter bees. The leafcutters scoop perfect circles out of the leaves on our rose bushes, which we don't mind so much. Leafcutter bees seem to be more interested in circles than leafcutter ants (whom you have probably seen on nature shows carrying various square-shaped leaf pieces on their backs).

Then there are the orchard‐mason bees, who burrow into wood and lay eggs in the holes. We found out it's pretty easy to attract them to the garden by drilling holes in old pieces of wood so they can nest in them. But the holes have to be precisely 3/8 of an inch in diameter, or you attract different species of bees altogether (how do they know?). And depending on how deep you drill the holes, you either get all males or all female bees — which just adds to the mystery! Knowing just what they like, and making a few more assumptions on top of that, we made a gratuitously elaborate bee box (copper‐roofed and mosaic-covered), with the rows of precisely‐sized holes for bees to build their cocoons in.

Later on, when we peeked inside our bee box, we realized that the leafcutter bees also use these holes. After inspecting some of the cocoons inside, and we saw that they were made of carefully‐cut, packed and dried flower petals. And sweetly, inside each cocoon of flower petals was a bee larva. The bee cocoons themselves looked like little multi‐colored, banded cigarettes, and seemed to be made with whatever flowers had been blooming the week the eggs were laid. The bees were using what was available at the time. After examining quite a few, we decided they are particularly fond of purple bougainvillea petals, green rose leaves, orange poppies and pink rose petals. These cocoons look like pieces of art. We added a large old oak barrel to our garden this spring to collect rainwater, but it turns out the bees love it! We hadn't thought of that, but of course bees need to drink as well as eat, so if you want to attract bees to your garden don't just plant flowers for them to visit, put out water, too. Here are some bees hosting a bee happy hour around the rim of the barrel.

Seems like every new thing we learn about the backyard bees raises more interesting questions. Why do they all group together and drink side by side? Is it because they're social insects and they prefer to be in a group? Are they perhaps getting very specific navigating instructions back at the hive that direct them not just to this water barrel, but to a very specific spot on the rim of the barrel? If so, how can their instructions be so precise? Or maybe this is just the best place to drink. They choose to line up on the rim, where it's very soft and saturated with water.

We also wondered, do they carry water back to the hive? Or is each bee just coming over for a drink when it's thirsty, and letting the other bees back at the hive fend for themselves? If you‘ve seen puffy yellow pollen‐packed bee legs, you know that they've figured out a way to carry pollen back to other bees, so maybe they've solved the water‐carrying problem, too.

So many questions, so many bees. We hope they're around for a long time so we can keep watching, and asking . . . and trying to figure it all out.

--Maria Sanders & Dan Holzner