Friday, August 19, 2016

Dog Bane

Silvery Checkerspot on early dogbane blossoms - REK
There are scattered patches of dogbane in our grassland, a species that most true farmers would consider a weed and try to kill but we save it for fiber.  Its scientific name is Apocynum cannabinum, the Apocynum meaning "poisonous to dogs," hence the bane of dogs.  It can also be toxic to cattle so we hay around the patches.

Milky latex
Its reddish stems ooze a white milky latex which can cause skin blisters. It is described as bitter tasting (there is always someone to try tasting) and contains cardiotoxic glycosides, the same family of chemicals as digitalis.  The roots had been used therapeutically in the past to treat heart failure.  With its bad taste, only a desperate horse or cow would continue eating it, but 15-30 grams of dried leaves reportedly will kill one.

Dogbane grows freely in fields and open areas, prefers moisture but is thriving on our upper hayfield.  The "cannabinum" might stir excitement in a lawman's heart but it comes from Cannabis as a fiber plant like hemp, and fiber is one reason why we protect it, but more on that later.

Spittlebug home - REK
There are a lot of insect associations with dogbane which add diversity to our otherwise boring fescue and Johnsongrass fields.  In spite of its toxicity, spittle bugs seem to love dogbane.

During the early summer most of the dark red stems have a little bit of drool concealing a tiny green bug, butt up in the air, blowing froth of dilute digested xylem out its rectum.  If you set aside the yuck factor and wipe away the bubbles, the little guys are actually cute!  These are the nymphs of froghoppers, little athletes capable of hopping 2 feet in the air.  They are well worth the blog focused on them alone.

Spittlebug exposed - REK

The broad head of flowers attracts a wide variety of pollinators including bees, flower flies, wasps, butterflies and moths.  The USDA/ NRCS ranks its value to pollinators as "very high."  Pennsylvania leatherwings (Chauliognathus pensylvanicus) are attracted to their pollen and their larvae attack many other insects.  Tachinid flies visit the flowers and lay their eggs on stinkbugs, Japanese beetles and other pests where their larvae grow up eating inside them until they die or at least don't reproduce.  Birds even use the fibrous fluff of the seeds for nesting material.

Milkweed is in the dogbane family (Apocynaceae), and a variety of "milkweed" insects visit ogbane as well.  Small milkweed bugs (Lygaeus kalmii) are attracted to them.  Dogbane is a host plant for several caterpillars including our beloved snowberry clearwing moths that mimic hummingbirds, nectaring without touching down.  Monarchs nectar on the flowers but their caterpillars can't survive by feeding on the plant.
Dogbane Beetle
I have left out one of the best for last, the dogbane beetle.  This gem literally changes color depending on the angle of the light, its metallic green sheen blending into gold and all shades in between.  According to Illinois State Museum:
"Chrysochus auratus iridescence "changes color because of stacks of tiny slanting plates, under which is a pigment.  Some light rays reflect from the surface of the plates, and other light rays reflect from the pigment underneath. At different angles, the light reflects at different speeds, causing interference and resulting in our seeing different colors that shine."
The eggs are laid in the soil or on the plant and the larvae tunnel in the soil to feed on dogbane or milkweed roots.  The adults are able to defend themselves by giving off a foul odor like many other beetles.  The best approach to them is to photograph them and enjoy them at a distance.

Colors we can't reproduce -  Nature Web
Dogbane cordage - REK
Ah yes, the fiber!  Hemp dogbane has been used for cordage by Native Americans for at least several thousand years.  The individual fibers that are found under the dry bark in the fall are stronger than cotton of the same size and found multiple uses from bowstrings to sandal soles.  Primitive skills instructors demonstrate the process at the Nature Center each year and you can learn to make your own cordage at this site.  We will be harvesting the dogbane this fall for the Wonders of Wildlife classes.

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