Garden Doctors: Insects damage plant used for dyeing wool

Julie R. writes: My passion and hobby is spinning and weaving? wool.? Within the past two years, I have been growing specialty plants that I harvest and use for dyeing my own spun wool.

One of my favorite plants that I use for dyeing beautiful colors is Coreopsis tinctoria. I recently visited the garden to pick the coreopsis blooms for a dye batch, but to my dismay, all the flower petals were chewed off by insects and only the centers of the blooms were left intact!

My “dye” garden is totally enclosed with a fine sturdy mesh (top and sides), so it is a mystery how the insects entered the garden and are responsible for the coreopsis petal damage.

Even more puzzling, none of the other plants in the garden have been affected, and they include tansy and plumbago. I tried to hose the insects off the plants, but that was not successful, as they moved and jumped about very fast.

I also tried picking off the insects and dusting the plants with a bug killer, but met with little success. I did manage to capture one of the insects to see if I could identify the culprit.

Under a magnifying glass, it actually looks like a very small grasshopper.

I can tell you that I have not found weevils, slugs, earwigs, caterpillars, cucumber beetles or leaf miners.

Help!

I suggest you contact the local University Extension office and take the captured insect in for accurate identification. True bugs have small immature offspring called nymphs that resemble the adults compared to, say, the larvae of beetles and caterpillars that are responsible for chewing damage on plants.

(Grasshopper nymphs are a quarter of the size of a mature adult.) Once the bug is identified, then you can be advised of the most effective control, whether it be biological or chemical.

I do have a thought about your mesh enclosure: You have done a good job keeping out deer and any other pests, but you have also kept out natural predators, insect-eating birds, that are effective in keeping damaging insects in check.

Still, how the unidentified insect/bug appeared is still a mystery and they simply must have slipped through the mesh enclosure.

More on coreopsis

Coreopsis, a perennial, also known as tickseed, is admired for its yellow blossoms and its showiness in the garden that does indeed attract insects both desirable and undesirable. It can be used as a “good” insect diversion when planted in a vegetable garden.

As an example, when it is planted near squash, cucumber beetles will attack the tickseed instead of the yellow squash blossoms. Yellow flowers attract our important pollinators such as bees and butterflies.

Coreopsis tinctoria, plains coreopsis, an annual flowering plant, attracts an array of beneficial insects and yes, as an added attribute, it is a source of natural dye used in yarns and fabrics. It produces a mahogany red dye for yarns that is surprising given that its petals are yellow.

Daphne W. writes: I am noticing an interesting event that I have never seen before. My neighbor has a moderately tall Arbutus unedo “Marina” near our garden and there are clusters of Monarch butterflies visiting the flowers.

What can you tell me about the attraction of this tree, since I thought Monarch butterflies preferred milkweed? Could they be a different species of butterfly that looks similar to the Monarch?

To answer your last question first: Viceroy butterflies do mimic Monarchs in appearance, but the difference is the extra black line across the Viceroy’s hind wings. They are easily misidentified from a distance.

The Monarch butterflies are nectaring on the Arbutus’ pinkish-white, bell-like flower clusters that appear from winter into spring. Arbutus unedo is part of the manzanita family and is a huge nectar source for the Monarch butterfly.

Milkweed, Asclepias spp., is an important larval food source (leaves) as well as a nectar source (flowers).

For those readers who are contemplating planting more butterfly attractants, you might consider introducing an Arbutus unedo “Marina,” a dwarf variety, that reaches a height of 6 to 8 feet, has the similar beautiful, reddish-brown exfoliating bark and shiny, leathery-green leaves of our native madrone.

It can be used as a hedge, but should be positioned away from walkways, since it is also known as a strawberry tree with its colorful strawberry-like fruits, which can be messy when they eventually drop.

Arbutus is also a nectar plant for the California Dogface butterfly, as well as a hummingbird attractant.

“Butterfly Gardening, Creating Summer Magic in Your Garden,” written by The Xerces Society and the Smithsonian Institution, is an excellent source for in-depth information on butterflies.

Dana Lozano and Gwen Kilchherr are garden consultants. Send your gardening questions to The Garden Doctors, at pdgardendoctor@gmail.com. The Garden Doctors can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.