Naturespeak A naturalist's view of the world

February 15, 2009

One for the Cutworm

Filed under: Uncategorized — wykes @ 6:46 pm

A February thaw is always deceiving. Even the slightest hint of warmth triggers an inner switch that causes us to say things like “well, Spring is right around the corner” or “I’m ready for winter to end.” Even though a cursory glance at the calendar would show us that the glass of bitter winter brew is only half empty, we choose to ignore the facts. This is a survival tool.  It is as valid as any employed by the wild creatures of wood and water, although somewhat dumber in evolutionary terms

Actually, we have turned the seasonal corner – it’s just that the route is more like a roundabout than a city block. Animals are responding to the change in the air. You’ll note that the Cardinals are beginning to sing, Horned larks are now performing a head to head bobbing dance, and the opossums are hurling themselves at passing cars with renewed vigor.  While I certainly plan on returning to these topics in future versions of Naturespeak, I would like to now call attention to cutworms.

It was just before Valentine’s Day when I encountered a juicy little cutworm crossing my driveway (see below). The heavy rain accompanying the recent thaw apparently drove the beast from it’s winter hibernaculum (over-wintering spot) somewhere on the north side of the drive and sent it packing towards an undetermined place on the south side. I, being in the middle of the drive, spotted it and picked it up. Even though the day was “warm” by winter standards at about 38 degrees F., the sight still took me back a bit. Seeing a fleshy caterpillar this time of year provided a nice reminder of the different strategies used by animals to get through the season.

Even though I don’t know what kind of cutworm this is, I am fairly confident that it is indeed one. Cutworms are the larvae of a large group of moths in the Noctuidae group. Telling them apart is about as easy as keying out the Goldenrods. As a group they are all covered with smooth skin decorated with mottled coloration. They characteristically roll up in to a “C” shape when disturbed and this one performed on cue (as you can see above and here in better detail). In addition to becoming a circular letter of the alphabet, the caterpillar in question disgorged a healthy amount of green spit onto my palm. All of this is done to look unappetizing and I’ll admit that I wasn’t even tempted to pop it into my mouth.  If someone had offered me a $10 bill, I might have considered it but…oh, well we’ll never know will we?

Among cutworms, there are those -such as the Black Cutworm- that overwinter as a pupae. Others, like the Clayback, Dusky and Army Cutworms, overwinter as larvae. My February driveway discovery wasn’t any of these latter species as far as I can tell, but it was obviously one in the larval overwintering school of thought. This tactic requires the ability to build up anti-freeze in the body fluids (which I happen to know are juicy and green!) in order to attain the ability to super-cool. Super-cooling doesn’t mean the same as super neat or really “with it,” it means the body can still function at levels below the normal freezing point of water. In fact, cutworms have been known to resume feeding during mild periods over the course of the winter. Eating grasses in the middle of winter, now, that’s cool.

Gardeners and farmers certainly don’t think cutworms are cool. These creatures can wreak havoc on all forms of turf and vegetable crops. A typical feeding pattern for this larvae is to emerge from the ground and cut down a tender shoot in the manner of a miniature lumberman with a saw. The severed stalk is chewed up and the stumps are left as evidence. This habit explains how the group got its common name. This also explains why some people have spent their entire career trying to outwit these things.

The recognition of cutworm damage has entered into the general folklore of farming. In the days before chemical sprays, it was custom to plant four corn seeds to get one surviving one. “One for the blackbird, one for the crow, one for the cutworm, and one to grow” was the motto. I’ve also seen this phrase as “One for the blackbird, two for the crow, three for the cutworm, and four to grow,” but even though the mathematics are the same, it’s more confusing. Either way, it was widely accepted that you will lose some of your crop to avian and insect pests, so you’d might as well get used to it. Crows and other blackbirds relish cutworms, by the way, so there might be some conversion factor needed to make this formula balance out at the bottom of the sheet.

I chose to release my worm, preferring to think he might freeze to death on his own sometime in the next few months. If he doesn’t, well, then he’s made the cut and deserves to live.  Hey, he’s only eating my yard and anyone who has viewed my yard will see that it will never make the cover of Golf Digest.  If, when it pupates in the spring and turns into a flying brown moth that goes into your yard, then you have my blessings to wipe it off the face of the earth. For now, however, it’s one for the cold cutworm.

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