Juniper Twig Geometer is Unknown “diamondback” Spanworm on Cedar

Subject: Help Identify
Location: Talbott, Tn 37877 in a 80 year old cedar tree
July 20, 2016 5:04 pm
My daughter recently found this little guy hanging from what appeared to be a spider web but upon further examination could have been its own silk. I have been told that it could be a chameleon worm but I can’t find any info to back it up. Can you help identify please? I would like to know incase my daughter finds another one I can tell her to either stay away or its safe to touch. Thanks in advance!
Bryan Hux
6th Grade Science
Jefferson Middle School
Jefferson City Tn
Signature: Bryan Hux

Unknown Spanworm
Juniper Twig Geometer

Dear Bryan,
Though we have not had any success with a species identification, we can tell you this is an Inchworm or Spanworm in the family Geometridae, and it poses no threat to humans as it is neither venomous nor poisonous.  We wish we could be certain that the cedar upon which it was found was also the host plant as we couldn’t find any similar looking Spanworms associated with cedar.  Perhaps one of our readers will have more success at a species identification than we have had searching BugGuide and other sites. 

Karl finds the ID
Hi Daniel and Bryan:
It looks like a Juniper-twig Geometer caterpillar (Patalene olyzonaria). Despite the name, the principal food for the caterpillars is given as cedars of all varieties. Regards, Karl

Thanks so much Karl.  We like our name “Diamondback Spanworm” since the BugGuide description is:  “Larva: body brownish or grayish with dark angular lines dorsally and laterally, creating a diamond-shaped pattern; whitish patches below angular lines in subdorsal area; pair of black dorsal warts on ninth abdominal segment; head brown and gray with dark brown herringbone pattern on lobes.”

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