An October Moth

Erannis tiliaria                 

After a week of unseasonably warm weather (in the 90s), the thermometer has synched with the season.  Frost this morning.   We have a wood stove - today will be the first time I've fired it up. As I headed out the sliding glass door in my living room and headed towards the woodshed, I noticed a pale, small (~1.5 inches) moth clinging to the door frame.  I didn't expect to see a moth so late in the year.  I took a quick, close look, but I didn't have a clue what species it was. It was chilly and I didn't put on a jacket.  So I continued on my way to the woodshed, picked out a couple of logs and headed back inside to get the fire started.  When the heat from the wood stove took the chill out of the air in the house, I picked up my little point-and-shoot camera.  It would only take a minute to get a picture.  That's all it I need to find out the name of my "October" moth.     No, I'm not an entomologist, but I know what they need for an identification.  I downloaded two photos from my camera - and sent them to my favorite insect ID webpage: BugGuide.net.

The answer arrived in my mailbox at 8pm:  it's a cold season, or "winter" moth - a geometrid known as a Linden Looper.   My October moth was doing exactly what the books say it should do.  Adults emerge in the fall and live to breed.  The small (1.5 inch) caterpillars are known as inchworms or loopers because of the way move.  The larvae hatch out in early spring and feed on leaves.  Their favorite trees?  Basswood (also known as linden).  But they don't appear to be picky.  They'll feed on aspen, elm, ash oak, maple, American hornbeam, hickory, apples and cherries too.

After a month or so of eating and moving from leaf to leaf on nearly invisible wisps of web, they burrow into the ground and pupate.  The adults emerge in October.  The wingless females emit pheromones that attract the winged males.  After mating, the females crawl up tree trunks and lay their eggs in crevices and under bark.

They over-winter as eggs.

Ever wonder what chickadees and nuthatches are doing when you see them inspecting tree bark?  They're going after these and other insect eggs.

Linden loopers are known to be irruptive - with population booms and busts.  And yes, they will defoliate trees.  But if you see them in your yard, don't panic and pull out the spray can - birds will take care of them for free.  These caterpillars are baby food for birds.  The moths are food for birds too - the late migrants and year-round residents.