After a rather slow start this spring, activity has picked up at Jerry Smith Park. Less than a month ago, not only were bees in short supply, but insects of all kinds were scarce. Now the prairie is buzzing, hopping, flying – even being chewed apart! The explosion of life in such a short space of time is truly impressive.
In fact, you can actually hear the prairie being eaten. Anyone who’s been snorkeling on a coral reef has experienced something similar – the crunch crunch of all those fish nibbling on coral is very similar to the munch munch of all the insects nibbling on prairie grass.
We may not think about it, but grass is crunchy. Too crunchy, in fact, for human teeth. That’s why you and I don’t put grass in our salads. Blades of grass have tiny bits of silica deposited in their tissues – like grains of sand or shards of glass. It’s hypothesized that these silica deposits are a defense against herbivores. (For some interesting experimental evidence of this, see Massey et al. 2006.)
Of course, for every adaptation there is often an equally powerful counter-adaptation. Silica deposits have deterred many potential herbivores like humans, but others have adapted over time. Large ruminants such as bison have evolved continually growing teeth to counteract the wear and tear of chewing on sand-paper-like food, while grasshoppers – master herbivores of the plains – have powerful, grinding mandibles that last long enough to get them through their life cycle.
I’m still amazed I could actually hear them as they ate.
Of course, I wasn’t there for the grasshoppers. Friday was bee-hunting day, and – thanks to a still-tight schedule on campus where we’re wrapping up the end of the semester – only my second collecting day this season, the first having been at the end of April. Amazingly, what I found on Friday was completely different from what I collected just three weeks ago.
At the end of April, the restored prairie site (Jerry Smith West) was the more active site, with the bright green Halictine Agapostemon dominating the scene. This time, bees were more numerous at the remnant prairie (Jerry Smith East). Moreover, instead of small, shiny Halictines, large, furry bumble bees (family Apidae, genus Bombus) were out in force.
Of course, with only two collecting days under my belt, it’s not possible to draw any general conclusions from these patterns – other than the fact that the bee community is incredibly dynamic. Within a few weeks, from one site to the next, you can see dramatic changes in what’s out there.
I also have – after just a short time with these marvelous creatures – a deep appreciation of the vital importance and shifting nature of the floral resources on which they depend. The wild flower crop where I found most of my Halictines just a few weeks ago is gone – and so are the bees I collected there. Now, a new crop of wildflowers has appeared on the remnant prairie and with it a new set of bees.
Bees apparently have to move – and move fast – as floral resources shift and change across the landscape. And they fight each other over access to flowers; I saw several aggressive interactions near a flowering bush on the remnant prairie site that seemed particularly attractive to many different types of bees.
All of this points to a sense of urgency in the life of a bee. Nectar and pollen are precious resources, perhaps even unpredictable. When bees find them, they hoard them aggressively, even chasing other individuals away.
All this to say that little patch of flowers you put in your garden for the bees and butterflies matters. It matters a lot, even if it flowers only for a little while over the summer, because the one period when your garden is flowering may make up for scarcity faced elsewhere by the bees in your area. And if you can manage to have different flowers blooming at different times across the summer, then you will have done even more help the bees of the world get by.
In other bee news, two of our mason bee boxes at Jerry Smith have been colonized! Both boxes had one tube filled by the end of last week, and both of these were on the remnant prairie. Mason bee females use hollow spaces to lay their eggs and provision young with nectar and pollen before sealing off the tubes in hopes that the larvae can grow and mature undisturbed. I actually saw an adult bee in one of the tubes when I checked the house, but I wasn’t able to get a photo of her. She was just too shy to come out while I was there.
I’ll be writing annual reports for work from now until the end of May, and I also have WisCon next weekend (yay!), so there won’t be any more bee posts until June. But June will be a very busy month bee-wise, so please check back then if you want to hear more. I know we will have some fun stories to share!