Subject:  Butterfly eggs?
Geographic location of the bug:  Los Angeles, CA on side of wood door
Date: 11/05/2017
Time: 03:31 PM EDT
Hello, I noticed a gray moth about 1 inch big sitting on the side of my door outside.  Then, I noticed that it seemed like the gray parts were falling off and then an orange yellow butterfly was underneath. The next day, the butterfly was gone, but there were tiny dark silver eggs in a triangle shape. I thought it was just a remnant, but then 2 days later, these tiny little bugs started growing out of the eggs, and now the eggs are all gone. I’m just wondering what kind of bug they are and why the butterfly laid it on the door instead of a leaf.  Will they all die and should I do anything? Thank you.
How you want your letter signed:  Lecia

Painted Tiger Moth Caterpillar Hatchlings

Dear Lecia,
Based on your location, your description of the “gray moth” and the “orange yellow butterfly [that] was underneath” and the images of these newly hatched caterpillars, we are quite confident that the eggs were laid by a Painted Tiger Moth.  As an aside, a clutch of similar eggs hatched on our office screen door this week.  The Painted Tiger Moth is a pretty gray moth with reddish orange to yellow underwings.  Painted Tiger Moths are attracted to porch lights, and they frequently mate and lay eggs on the walls of homes that have lights that attract them.  Painting Tiger Moth caterpillar hatchlings look exactly like your images.  Painted Tiger Moths do not feed as adults and the female will die shortly after laying eggs.  It is possible the individual on your wall died and began to fall apart, first losing the wings which is why you thought the “gray moth” had a “orange yellow butterfly … underneath.”  Painted Tiger Moth caterpillars are generalist feeders that will eat a wide variety of weeds and other low growing plants in the yard.  For their first meal, they eat their egg shell and that provides them with the necessary energy to disperse in search of food.  It will save them a trip if you relocate them to a part of your yard with tender green sprouts, but they will also fend for themselves, though we imagine many will not survive. 

Painted Tiger Moth Caterpillar Hatchlings

Thank you so much.  I believe that you are right. Their eggs are completely gone now.
I really appreciate it. I Will try to move them to some leaves.

Lecia Harmer
Location: Los Angeles, California

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