The trails at Silver Creek Metro Park in Summit County are taking on a pre-autumnal tone with their fruits of fall arriving. There are the porcelain blue fruits of silky dogwood (Cornus amomum) and the white fruits and bright red-purple pedicels and peduncles (fruit stalks) of gray dogwood (C. racemosa), there are rose hips and the poisonous deep purple-black fruits of pokeweed. At Secrest Arboretum we saw the wavy leaves of the fernleaf beech, an elegant smaller variation of beech, with perfect rounded crowns. There were frilly flowers of ‘Pink Spice’ bugbane (Actaea), a member of the buttercup family. There were scalloped green leaves of katsuratree and the occasional apricot-colored version presaging their coming fall color.
Last week I wrote of galls — abnormal plant growths induced by gall makers, especially those induced by gall wasps on oak trees (well over 800 different types), and then pictured the lobed oak gall, found on a swamp white oak at Ohio State University's Secrest Arboretum in Wooster. I closed with a galling quiz question (from a 2021 article in the New York Almanack): “What do the following items have in common: the Declaration of Independence, Leonardo da Vinci’s notebooks, Bach’s musical scores, Rembrandt’s drawings, Shakespeare’s plays, and the Magna Carta?”
The answer is they were written in oak gall ink! From medieval times to the 1800s, insect galls — especially on oak, containing tannic acid that strengthens the gall wall — when blended with iron salts produced a dark, inky precipitate. This iron-oak gall ink binds well and sinks into paper, making it a durable ink for preserving documents. It is no longer the go-to ink for documents, but you can experiment and make your own.
Last week my grandsons and youngest daughter, visiting from the Big Apple, found a beautiful caterpillar on one of our backyard white pines. It was orange-red, kind of gummy-like, with large sucker-like prolegs, four knobby horn-like projections on the head, spots along the abdominal segments, intensely hairy, and about 1½ inches long when unfurled.
Since Grandpa and Mom are supposed to know things, we embarked on determining the identity of this caterpillar. It was a challenge, especially because caterpillars may dramatically change colors with different stages. These stages are termed instars.
The later instars of this insect are the ones usually noticed, and indeed I have seen them before, as they are quite large (up to 3-5 inches long) soft and green, or sometimes white or intensely black. But orange — so confusing. We cycled through numerous guesses; we toyed with the idea that it was the hickory horned devil (which is related) and further afield to the pandora sphinx. We phoned a friend, Joe Boggs, an OSU entomologist in Hamilton County, and he identified it as a first instar imperial moth caterpillar, Eacles imperialis imperialis.
It feeds on a wide range of plants including pine, of which our other candidates did not, which was an early clue. After growing bigger and changing colors, and if avoiding becoming bird food, this caterpillar burrows into the soil, becomes a black-colored pupa, and then metamorphoses into a yellow and brown moth, although identification of the moth is also a challenge as male moths add mauve patches on their wings.
Plant Lovers' Almanac:More about the bugs and the bees
Plant Lovers' Almanac:Aphids and other problems for plants
Note: Adult insects of course have six true legs, occurring on the middle insect segment, the thorax. Prolegs of caterpillars are different; they are on the abdomen, the segment behind the thorax. These prolegs often have adhering suckers that grasp twigs and leaves.
Prolegs are helpful in insect identification. For example, caterpillars (Lepidoptera order), which are the larvae of adult butterflies and moths, have three to five pairs of prolegs, while the caterpillar-like larvae of many sawflies (Hymenoptera order), such as the dogwood sawfly or the European pine sawfly, have six or more pairs of prolegs. This difference is very useful to know if control of these insects is deemed important, since different insecticides are effective on Lepidoptera and Hymenoptera.
Plant Lovers’ Almanac:Hydrangeas, Japanese beetles and a 200-year-old bur oak
Recently Matt McClellan from Nursery Management magazine visited Secrest Arboretum to research an article on our crab apple collection (Crablandia) where for decades we have evaluated over 75 types of crab apples (apples with fruits 2 inches or less in diameter at maturity) in our replicated, randomized plot. We rate these crab apples for disease resistance and aesthetic characteristics. We discussed the new Japan red rust disease that we discovered at Secrest, found for only the third time in North America a few years ago, and enjoyed these lovely flowering trees, that also qualify in a value-added sense for an edible landscape, as evidenced by my wife’s and nurseryman Mike Lee’s Dolgo Crab Apple Butter. Here is the recipe:
• 8 lbs. of Dolgo crab apples
Wash the crab apples in a large kettle and cover with water. Heat to a boil. Simmer until fruit softens. Drain, then process through a mill. To the sauce add the sugar, cider, cinnamon and cloves. Simmer under low heat or use a large crockpot for 1½-2 hours. Stir occasionally. Pour off the hot Dolgo butter into jars. Process in a hot water bath or freeze. Ruby-red and tart; use as a chutney on turkey or on hot sourdough bread.
As Mike notes, the house will then smell great.
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Our Plant Problems Diagnostic Workshop at Secrest last week had almost as many samples on tables indoors as we did attendees: 72 and 80, and then many more outdoors: from a dozen fungal, insect and mite galls to late-season leaf spots on redbud. From the reddish-brown anthracnose lesions characteristically along leaf veins of yellowwood to bot rot fungal cankers causing stem dieback on viburnum. From horticultural oil injury on spruce causing yellowing and greasy discoloration, to Guignardia leaf blotch that plagues Ohio buckeyes but not bottlebrush buckeye.
The diag-mosh-tics pit of enquiring minds discerning and discussing plant diseases, insect pests and nutritional problems was great fun. The workshop was for the green industry and home gardeners alike.
Plant Lovers' Almanac:Potato, po-tah-to, tomato, to-mah-to, let's learn more
Sometimes we made mistakes, but all adhered to the wise words of the 18th century botanist Linnaeus: “If you have remarked errors in me, your superior wisdom must pardon them. Who errs not when perambulating the domain of nature? Who can observe everything with accuracy? Correct me as a friend, and I as a friend will requite with kindness.”
Jim Chatfield is a horticulture educator and professor emeritus at Ohio State University Extension. If you have questions about caring for your garden and other topics, write to chatfield.1@osu.edu or call 330-466-0270. Please include your phone number if you write.