How to Be a Good Host (to caterpillars and other creepy-crawlies)

I mentioned in a previous post that I only recently learned that my practice of carting away leaves and old plant stems in the fall is likely contributing to the decline of the local butterfly population (see “Life in the Leaf Litter,” “Six reasons to NOT clean up the garden this fall,” and the related “4 Reasons Not to Rush the Spring Garden Cleanup”). This post is intended to provide links to more information on the topic of host plants for local fauna.

Red admiral on coneflower

First, some terminology.

“A [North American] native plant species is one that occurs naturally in a particular region, ecosystem, and/or habitat and was present prior to European settlement” (definition from Wild Ones).

A native plant grown from seeds or divisions is a straight species native plant.

A nativar is a cultivar of a native plant. (A cultivar is a plant type produced by selective breeding.) Plants are selected for reproduction on the basis of certain characteristics “to the exclusion of the inherent variation found in nature” (Wild Ones).

An obligate larval host plant is a plant that is required by an insect species. The adults might take nectar from a variety of plants, but they will lay their eggs on, and the larvae will feed on, only one or a few species (e.g., monarchs and milkweeds).

According to a recent article in the Star Tribune, planting “for the express purpose of feeding insects” is “a seismic shift in gardening.” The article provides a short list of Minnesota butterflies and their preferred host plants.

A post from the University of Minnesota Extension talks specifically about little bluestem (Schizachyrium scoparium) and the butterfly larvae known to feed on this native grass, including Dakota skippers and several other species of skippers. Interestingly, the only photo in the post shows a cultivar of little bluestem rather than the straight species.

Are cultivars/nativars as useful to wildlife as straight species? For some opinions on this topic see this article from the Rochester Post Bulletin and this from the University of Missouri Extension, both positive. On the more negative end of the spectrum, see this position statement from the Wild Ones, this article from the National Wildlife Federation, and this from EcoBeneficial.

To learn more about host plants other than milkweeds, start with the Native Plant Finder from the National Wildlife Federation, this article from Minnesota Gardener Magazine, and this list from the U of MN Extension. It’s a short list, but additional links and sources are noted.

If you’re more interested in birds than butterflies, note that “96 percent of all birds need insects as part of their diets at some point in their lives – even hummingbirds. … [H]ummingbirds feed their young a certain kind of native bee, and that bee feeds on a native plant: New Jersey tea (Ceanothus americanus). It’s a 3-foot tall shrub with white flowers that bloom from June through August” (quote from the Minnesota Gardener article in the previous paragraph).

Many of the plants mentioned in the sources listed above are readily available from native plant nurseries. Others are harder to come by. I read in Native Plants of the Midwest by Alan Branhagen that Canada plums “host so many creatures that their foliage can look tattered by midsummer.” Branhagen adds: “The gorgeous flowering cultivar ‘Princess Kay’ has been selected from wild Minnesota stock for superb double flowers equally as exquisite as any oriental flowering cherry but providing no nectar for pollinators” (p. 172).

I thought it would be nice to tuck one of these plants into a corner of my yard, but finding straight species Prunus nigra isn’t easy. ‘Princess Kay’ is available from several nurseries, but the only source of non-cultivar Canada plums seems to be seeds from Gardens North. Do I want to grow a plum tree from seed? As the old saying goes, the best time to plant a tree was twenty years ago. When their seed sales re-open in September, I may just send away for a packet.


Why “House Without Hostas”?

Hostas. What’s not to like? They’re hardy, handsome, reliable, varied. As far as I know, they’re not an invasive species in Minnesota. I don’t have anything against hostas. In fact, I have several in my front and back yards right now, so my family currently lives in a house with hostas.

We're still a house with hostas for now

I chose “House Without Hostas” as my blog title to reflect my personal goal to gradually replace most of the non-native plants in my yard with plants native to the Twin Cities area (east-central Minnesota). Native plants are tough, attractive, and, most importantly, vital to the birds, insects, and other animals we share our space with.

An older friend observed the other day that it seems like there aren’t even half as many butterflies as when he was a boy. But when he was a boy, there was a lot less hardscaping and turf grass. More land was covered by woodland, orchards, unkempt meadows, and farm windbreaks. Pesticides and herbicides were used, but not to the extent they are today. There was more tolerance for yards to be a little weedy and disheveled, at least around the edges. With bagging mowers, leaf blowers, and pump-sprayers in every shed, our standards have risen.

Most of us go with the flow, planting whatever catches our eye at the garden center, maintaining our lawns, cleaning up yard waste every fall. But did you know that cleaning up leaves and dried stems in the fall is yet another blow to butterfly populations? I wasn’t aware until recently that many butterflies overwinter in garden duff as eggs, chrysalises, and even caterpillars. In my zeal to get things cleaned up in the fall, I’ve likely been sending baby butterflies to the compost site along with the fallen leaves and dried plant stems.

Goldfinches eat the seeds of my cornflowers, and some bees and maybe even a few hummingbirds visit my hostas. But do these plants host the native insects and the moth and butterfly larvae that provide food for animals higher up the food chain, especially birds? We know that monarchs need milkweeds, but many of us don’t realize that other species also have what are known as “obligate larval host plants”; Karner blues depend on wild lupines, fritillaries need violets, skippers utilize wild grasses, and several species need oaks, ashes, wild cherries, or willows. (Interesting note: It was Vladimir Nabokov who identified and named the Karner blue butterfly. It seems he was as passionate about lepidoptery as he was about writing.)

See this post for more information on wildlife host plants and whether cultivars and “nativars” are as beneficial as “straight species.”

A little history (with before and after pictures!)

We bought our house in Arden Hills, a suburb just north of St. Paul, in 1998. Here’s what it looked like when we moved in. (We had already cut back the shaggy bushes on top of the retaining wall.)



Within the first few years, we had buried the power lines in the back yard, pulled out the overgrown bushes in front, and had the gray rocks from the retaining wall hauled away by someone who saw our ad on Craigslist. We had new rocks installed to create a rock garden by the driveway, and this is what things looked like somewhere in the early 2000s.



As time went on, we had the warped board-and-batten siding replaced, put up a fence, put in a boardwalk on the west side (where it’s always soggy in spring), made some adjustments to the back deck, and smothered the lawn and put in wildflowers on the east side.

Continued tweaking over the years brings us to the present day.




Getting better, and it only took 19 years! In addition to swapping out some of the non-native plants, I hope also to expand planting beds, add structure with more shrubs and native grasses, and continue to reduce the size of the lawn. I’ll share more about projects past, ongoing, and future in upcoming posts.