But few people have one. And that’s a situation I’m trying to change.
A couple of months ago, I put away some seeds from the pawpaw trees in my yard, with the idea of starting and giving away pawpaw seedlings in the spring. Preserving viable seeds turned out to be quite a process (Post #G22-062). After a thorough cleaning, the seeds need to be kept moist, and kept cold over the winter. So a couple of plastic bags of seeds-in-damp-potting-soil have been living at the back of my fridge for the past two months.
Today it was time for a mid-season checkup.
They’re still brown (no evidence of mildew or fungus). And they’re still damp, though it’s clear that they have dried out somewhat, so I’m going to top them off with a bit of fresh water. (In hindsight, I should have weighed them before I tucked them into the fridge.)
But, in general, things are proceeding according to plan.
Except that I don’t actually have a plan. I started this in response to a request for pawpaw seeds. I noted how difficult it seemed to be to come by pawpaw seedlings locally. And pawpaws are the only known host of the zebra swallowtail butterfly.
So when you get right down to it, my entire rationale for doing this is butterflies (aw!).
And thus I have fallen into the classic charismatic megafauna trap. As humans, we focus on saving animals that are attractive (pandas). Or noble-looking (elephants). Or have cultural context (bald eagles). Or, in this case, cute, and the Virginia state insect (zebra swallowtail butterfly).
The dead of winter is the perfect time to step back and take a more objective look at this effort. Given that we’re in the middle of the great insect apocalypse, and given that growing trees in suburban yards is more-or-less a zero-sum game (if not a pawpaw, then some other tree), what is it, exactly, that I’m hoping to accomplish.
Is propagating pawpaws the smart thing to do? Aside from the technical gardening challenge of doing this, and helping one insect (because it’s so cute!), is this really the best use of my time?
A summary of expert advice for an insect-friendly urban environment.
As my first attempt at being somewhat more systematic, let me use Google to find seemingly-serious websites offering advice on how to create an insect-friendly urban environment.
To frame that properly, I need to state clearly that urbanized areas constitute only a tiny fraction of U.S. land area. So, from the outset, this list is going to be oriented toward personal actions that residents of urbanized areas may take. My little survey clearly is not going to have the right “weighting” in terms of global impact, because those urbanized areas constitute such a small part of the entire U.S. insect habitat.
You can look at that any number of ways, and arrive at the same conclusion. The U.S. Census has a formal definition of what it considers to be an urbanized area:
Source: Census data via University of Texas.
Bloomberg has a nicely detailed summary of U.S. land use. You reach much the same conclusion from that as you do from the map above. Urban areas account for a few percent of the total land area of the U.S.
Source: Bloomberg, Here’s How America Uses Its Land,By Dave Merrill and Lauren Leatherby,
So, almost beyond a doubt, policies or actions applicable to the other land categories will have a much larger impact than what gets done in urbanized areas. Pasture/range, forest, cropland, and parks (and other special-use lands) vastly outweigh urban areas in terms of insect habitat.
The easiest way to quantify that is to focus on the diagram above. Roughly speaking, there’s one acre of crop land and two acres of pasture/grazing land for every resident of the U.S. Most of the production from that land is consumed domestically. Adults consume more than kids. If I had to guess, I’d guess that growing a year’s food for two U.S. adults takes up at least six acres of land. Compare that to my suburban lot, and, arguably, what I choose to eat is going to matter a lot more than how I landscape my yard.
But you do what you can.
For urbanites.
That said, below I have tabulated the advice most commonly offered to Joe and Jane Urbanite, to help protect and preserve the insect population. This is literally the first nine reputable sources that showed up in a simple Google query of best things to do to help insects. The full tables may be a bit tough to read, so scroll down for just the good parts.
Just the useful bit:
When I start from this perspective, I’m pretty sure that displacing other species of backyard trees, in favor of pawpaws necessary for a single butterfly species, is probably not the most effective thing I can be doing to help beneficial insects survive in my yard.
#1: Overwhelmingly, the first piece of advice is to reduce the area of your lawn, in favor of … well, just about anything else. Eight of nine sources said some version of that. Minimally, don’t mow it. Maximally, return it to more-or-less a wild area. Maybe plant it with wildflowers. Maybe plant it with insect-friendly plants.
I think I’m going to take this one to heart next year, as I have a large section of my back yard currently covered in black plastic, trying to kill the weeds. And a whole lot of saved flower seeds. I think that’s all going to become a flower bed next year.
#2: Skip the pesticides and herbicides. I think I have that one knocked. The more I grow in my vegetable garden, the less inclined I am toward any type of insecticides. Herbicide? I spell that h-o-e.
#3: Address your outdoor lighting. I had no idea this was quite so much of an issue. Everyone gives the same advice. Minimize outdoor lighting. And if you use outdoor lighting, go toward the red/yellow/amber spectrum, not white. Apparently, there is some truth to the idea that old-fashioned yellow bug lights attract fewer bugs. What also appears true, however, is that the switch to LED street lights. however good that is from the standpoint of reducing energy consumption, is a step backward in terms of harm to the insect population. Apparently, those old fashioned yellow high-pressure sodium lights were reasonably benign, compared to the white light issued by LED or mercury vapor/halide lamps.
For me, this is fixable. I have exactly two small outdoor lights. Both have white bulbs in them. I’ll swap those for bug lights, and problem solved.
#4: Create bee nests, bug hotels, and other protected habitats. Or, alternatively, just leave the edges of your yard looking like crap all the time. That works for me. I now have a great excuse for leaves, branches, pine cones, etc. along the margins of my yard. It’s not sloth, it’s environmentally sound policy. Plausibly the wilder it looks, the more insect-friendly it is.
But you can also buy bits of made habitat. I bought one of those solitary-bee or mason-bee nesting boxes in Spring 2016. Never touched it. Here’s how it looks this morning:
To me, that looks like an underwhelming amount of new-bee production for six years. A lot of the tubes remain untouched. Maybe a half-dozen have clearly released a live bee, as evidenced by the hole in the end of the mud. A few more might hold bees that will emerge this spring. That said, those bees will re-use those tubes, so it’s not clear exactly how many bees this investment produced. Or, for that matter, whether those bees would simply have laid their eggs elsewhere, absent this cute little device.
That said, I already own a couple, so I guess I’ll get the refill tubes, clean them up, and re-hang them. What could it hurt?
I’m going to stop there, except to note that planting native plants (such as pawpaws) is pretty far down the list. And so, as I had begun to suspect, it’s likely that going to all this effort to produce pawpaw seedlings is not very efficient. Laboriously saving the seeds, to produce the seedlings, so that others may displace some trees in their yard with pawpaws, so that the zebra swallowtail has a place to lay eggs … that’s a positive thing to do, but it should hardly be first on the list.
Best guess, after fixing my outdoor lighting, the single smartest thing I can do is transform large portions of the edges of my yard to wildflowers. Around here, it takes considerable effort to keep “wild” patches of yard from being overgrown with less desirable plants. So it’ll take some doing to get a setup that has any hope of maintaining itself, even if I mow it once a year to keep the trees down.
After that, it’s probably a question of being pickier about what I eat. I’m not sure about the extent to which eating organic produce actually avoids use of pesticides, rather than merely substitutes some classes of pesticides for others. But I am pretty sure that foods vary widely in terms of the average amount of pesticide and herbicide used per edible calorie. I think my next step is to see if research can generate any reliable information on that.
