I went to a great talk offered by the East Multnomah Soil and Water Conservation District on pollinators.  The talk I attended was part of a series that are free and open to the public. The schedule can be seen here. The take away for me was that it’s easy to provide at least some of what pollinators need without renovating your entire landscape or planting exclusively native plants or even putting a lot of energy into cleaning up your garden. In fact, it’s better for the insects and birds if you let your garden run a little wild. I’ll get into that further on.

Insects are animals too

This talk was given by the enthusiastic entomologist, Celeste A. Searles Mazzacano. Slides from her talk can be seen here. One of the first points she made is that insects are wild animals too, but because they’re small, a single homeowner can effectively create a wildlife preserve for insects in their own yard. A lot of insects don’t move more than several yards in a lifetime if they can help it. And their life cycles are so short you can house generations of insects even if you’re renting your property or do most of your gardening in containers. By contrast, if you wanted to accommodate a single top predator like a wolf, you’d need to provide a minimum of 10 square miles for 6 years. And instead of providing the service of pollination, they might eat you.

Bee pollinating Camas

Who are Pollinators

Most people think of honey bees as the main pollinators, but there are many other kinds of bees that pollinate too: bumble, mining, mason, laeftcutter, orchard, sweat, digger, and carpenter bees. As well there are wasps, flies, beetles, moths and butterflies. And to some degree hummingbirds and bats pollinate too.

Pollinators of the Willamette Valley

But it’s the different kinds of bees, with their fuzzy bodies that are particularly effective pollinators. The fuzz scoops up pollen on the way into and out of flowers and is held by the friction of the fuzz and also a mild electrostatic charge that builds up as they move, like socks on a carpet. Some of the pollen also gets scraped off and left behind when they land on subsequent flowers, thus achieving pollination. Bees are also the most motivated and persistent pollinators because nectar and pollen are their exclusive food supply which is not true of some of the other dabbler pollinators, who are just snacking on these foods. Wasps, for example, would rather eat your hamburger.

What is the Problem

The problem is all the usual problems that plague wild animals: habitat loss, pesticides, and diseases. The catastrophic recent issue called ‘colony collapse’ may be the result of parasites that flourish in managed bee mega-populations that are trucked around the country to pollinate monoculture crops. These mega populations bee ‘herds’ are needed because the typical monoculture crop system means that all the flowers in that crop become ripe at once. So there’s no food for pollinators until there’s way more than they can get to and pollinate in time. And housing that many bees together means disease spreads quickly within the herd and is then rapidly transported to native bee populations as the trucked bees are moved around the country. This results in declining bee populations across the board, in rural and urban areas.

The other issue with the huge monoculture crop fields is that it is simply too far for a flying insect to reach the middle of the field from their nests at the edge of the fields in the scraps of forest or hedgerows or undisturbed soil that remain. What’s needed is a development pattern across the fields of interspersed undisturbed areas with available habitat and flowering food supply to sustain the insects throughout the foraging season.

Vast monoculture crop

Similarly, in the urban setting, the majority of land is paved over or built on and what green space does remain is typically fairly sterile as habitat, consisting of mown turf, few native plants, and limited annuals and perennials which are often considered too high maintenance or informal. Again, incorporating ‘islands’ of insect habitat in this setting would go a long way to supporting pollinators in the urban environment.  Since they do not fly for the most part, it is a convenience with pollinators that their habitat does not have to be continuous as long as it’s not too far between ‘islands’. Each residential yard or commercial landscape or schoolyard that is adapted to include pollinator friendly features adds to the network of ‘islands’ across the city.

And of course just to underscore the big problem: if we lose our pollinators, 70% of our food crops will suffer and fail. (The other 30% don’t require pollination.) So it is a serious food security issue in addition to the issue of the survival of the individual insect species.

What can we do to help pollinators

In the urban and suburban settings these are some of the recommended strategies:

  • Try to plant at least 15% native plants in your garden. Pollinators are best fed and housed by the plants they evolved with (see our blog post on ‘Why Native Plants Really Matter’ here) but a garden does not have to be exclusively native to support them. Specifically, native plants from your ‘ecoregion’ are most useful. The term ‘native’ might include a plant from the high desert of Oregon strictly speaking, but for the native insect of the Willamette Valley, eastern Oregon’s high desert may as well be the moon and their chemistry would not recognize that plant. See here for a free downloadable guide to Willamette Valley natives.
  • Provide plants that successively flower across the long active season for pollinators, from about March to October here in Portland. Consider providing spring flowering plants like: Red flowering current, vine maple, crabapple, camas and Oregon grape. Summer flowering plants (easy, this is most plants) like: mock orange, salal, spirea, milkweed. And fall flowering plants like: asters, goldenrod, seaside daisy. Here is a useful free guide to local pollinator plants and bloom times.Early Flowering Vine Maple
  • Avoid treating your garden with insecticides if at all possible (see our blog post on ‘The Case of the Disappearing Insects’ here). These chemicals are not targeted and affect all insects, ‘good’ and ‘bad’. It’s likely that different ‘bad’ insects will move into the sterile territory after you apply these chemicals anyway and you’ll be stuck in a cycle.
  • Leave dead flower and grass stalks and decaying wood in place over winter. Insects burrow into these materials for the cold months and you may be shipping out your pollinators in the green bin if you clean up too aggressively. Better to wait and cut back plants in late spring after the insects have emerged.
  • Provide a range of sizes of ground covers, shrubs, and trees to create cover, shade, and variety to attract the most diverse range of insects and birds.
  • Group plants in clumps of 4 or 5 rather than spreading them out individually across a yard since it’s a long way for an insect laden with pollen to fly across a yard.
  • Mulch is useful but consider leaving some soil exposed for the mason and leafcutter and other bees and beetles that burrow into the ground to make nests.
  • Provide shallow trays of pebbles saturated with water to allow insects to sip water without getting stuck by the surface tension of a deeper water source and drowning. Potted plant trays filled with gravel and topped up with water work well.
  • In the rural setting: the same speaker, Celeste A. Searles Mazzacano, informed us that she offers a version of her talk for application in the rural setting as part of the East Multnomah Soil and Water Conservation District’s Rural Lands Program. That link is here.

-issued by Kyla Tanaka


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