Friday, May 25, 2012

Onosmodium and Larva

There are certain caterpillars that I see each year, but by the time they become noticeable, they’re of a fairly large size.  I’m making an effort to see some of these at their earliest stage of development, so I can get an idea of their life history.  A good example is the caterpillar I find on the False Gromwell, Onosmodium molle var. hispidissimum, in late summer.  I’ve never seen the earlier larval stages.  I don’t even know its species.  I just call it the Onosmodium moth.  I have run into people who know this moth and they call it the "Oh yeah.  I know that, but I can't think of the name."

I’ve been watching the Onosmodium since it emerged and have recently noticed some signs of leaf feeding.  The damage was concentrated in the area of new leaves at the top of the plant.

By folding back the developing leaves, I was able to trace the evidence of feeding right down to the emerging flower buds at the center of leaf formation.  Damage on the old leaves matched that of the newer leaves, so the feeding probably happened when the leaves were young and closely wrapped.

As I folded back the final leaf, I discovered this small larva at the heart of the new growth.  This part of the plant will soon unfurl into a long stalk of flowers.  I’ve noticed in the past that the larvae begin feeding on the flower stalk and later move down to the stem leaves.

I don’t know yet if this is the same species of larva that I’ve seen in the past.  I’ll keep watching its progress.  No matter what it is, I’m sure that I’ll learn something of interest through frequent observation.

Onosmodium was an uncommon plant at Blue Jay Barrens when I began my management activities.  It forms a large seed that is easily stripped from the plant, so I began collecting the seed and scattering it around the immediate area of the plants.  Areas along trails got the most attention and this Onosmodium patch near the trail head has grown from a few plants to several hundred.  There’s plenty of food here for the Onosmodium moth.

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