Missouri Master Naturalists- Springfield Plateau Chapter

Tuesday, August 6, 2019

Becky's Decorated Moth

Find the caterpillar on a zinnia flower head - Click to enlarge - BS
Becky Swearingen sent us this photograph to identify a caterpillar feeding on the composite flower head of her zinnias.  We couldn't even find it until we had closeup macro views.  After zooming in on the photograph above, watch her video here to see it in action.

Dressed up for a date with a flower - BS
This cool cat is a waved-lined emerald larva, Synchlora aerata, also known at the camouflaged looper.  It decorates its back with fragments of the flower heads it eats, (Aster, Rudbeckia, Liatris, Solidago, etc.) changing its appearance depending on the host plant.  This gives more meaning to "You are what you eat."
The fresh fragments blend in with the flower head, concealing the caterpillar until it moves.

Loopers or inch worms are members of the Geometridae family, from the Greek meaning "measure the earth."  The earth may be a slight exageration but they certainly can pace off a flower head.  They come equipped with only two or three pair of legs on the back end instead of the usual five pair of other lepidoptera larvae.  They use the hooks on the front legs to hang on while bringing up their rear to clasp before stretching forward again.

Decorated cocoon - Wikipedia ES
When the larva molts, the decorations remain on the old skin (exuvia) and gives it a chance to develop a whole new look, as by then its decorations have dried and turned dull.  Likewise, when it forms its cocoon, the decorations remain, giving it some further camouflage.



Wavy-lined emerald moth - Wikipedia
The larva decorations are a unique trait among moth caterpillars, found only on
S. aerata and S. frondaria found along the east coast.  The technique is different from the bagworm moths, Psychidae, that spin their case of silk and leaf fragments, carrying it along like a light weight motor home.  There are a few other species of insects which decorate their backs, the subject of a future blog. 
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Thanks to Phil Koenig from BAMONA for information on the genus Synchlora.  Also to Dr.  Becky Swearingen for the inspiration, the caterpillars and the photographs.