Insect superfoods

Visiting Coastal Maine Botanical Gardens this week brought some encouraging news about insect-friendly plantings. The designers had showcased many of the same flowers I’m growing to attract insect visitors, some inside the butterfly house near the entrance to the garden. Monarchs fluttered around this enclosed space, lighting on swamp milkweed and purple coneflowers. I spotted two species of caterpillars on stalks.

Monarch on purple coneflower in the butterfly house

   
    Planting for insects isn’t just for pollinators. It’s also intended to help leaf-eating insects, particularly caterpillars of moths and butterflies. 

Monarch caterpillar

Therefore Thomas Berger performed a useful service by cross-referencing lists of the best plants for these two purposes to derive a master list of insect “superfoods” posted by the Ecological Landscape Alliance. At the top of the section on herbaceous plants were goldenrods, asters, and sunflowers.

    Goldenrods support 11 species of specialist bees—bees that can only feed on a limited group of native flowers—and 115 kinds of lepidopteran caterpillars (caterpillars of butterflies and moths). Asters and sunflowers aren’t far behind. Goldenrods attract monarch butterflies and feed their caterpillars, making them second to milkweeds for supporting these fast-disappearing butterflies. 

    This is good news for my garden, because lots of goldenrods and asters are growing here already. I started some goldenrod from seed years ago. Patches of goldenrod here and there mark its spread around the yard. Unfortunately I didn’t keep a record of which species I’d planted. From photos, I suspect it was blue-stemmed goldenrod, Solidago caesia. Two years ago I bought some sweet goldenrod, Solidago odora, for a new perennial bed. Both native species have proven to be easy to grow and free-flowering.

    Goldenrods are members of the Compositae, also called Asteraceae, a useful family of plants because their central discs are made up many tiny flowers, each with pollen to offer. 

Visiting a daisy flower is an efficient way to collect pollen

The “petals” of the daisy-shaped blooms are actually strap-shaped flowers too. So an insect visiting one of these composite flowers gets lots of pollen with minimal travel. Goldenrod blooms are small, but if you look closely, you’ll see they share the family shape. 

Goldenrod's tiny daisy flowers

 

By the way, goldenrod doesn’t trigger hay fever. It has sticky pollen that doesn’t blow around like that of real culprits, such as ragweed.

    I’m growing some New England asters (Symphyotrichum novae-angliae) with pretty blue flowers. But aster volunteers are much more plentiful in the garden. In the past few years, a white-flowered type has popped up in lots of part-shaded spots with no effort on my part. I suspect it’s white wood aster, Eurybia divaricata.

Aster volunteers

    Last week I wrote about my bad luck growing sunflowers. I learned from Berger’s post that Helianthus annuus, the garden or field sunflower, was brought to New England by Native Americans as an agricultural crop and isn’t native here, although our local specialist bees can still use it. A native option is woodland sunflower, Helianthus divaricatus. Meanwhile, I’m growing oxeye sunflower, Heliopsis helianthoides, also called false sunflower, a different native genus but useful to pollinators too.

Oxeye sunflower