Finally! Early this spring, coming back from the mailbox, I noted a brown glob about the size of my fist on one of my fir trees. On closer inspection, I saw several irregular blobs which all turned out to be bunches of brown furry caterpillars, each a little over an inch long. I wondered what they might be when they grew up.
So the next day I selected a branch on which there were only two individuals and covered it with a jelly strainer sack, choked onto the branch with a rubber band. Over the next many weeks, I periodically moved them when they consumed all the needles on the branch tip, each time emptying the sack of shucked off skins and frass (the technical word for bug poop). I really wanted to know what they would turn into. Each time I had to make doubly certain no earwigs got into the covering. Earwigs are omnivorous and I’ve had problems with them in the past when I tried to do this. Several times half a dozen or so of these European invaders hid in the folds of the bag where the netting bunched up.
Just a week or so ago, I noticed the larvae were gone, replaced by little fuzzy ovals. Yee ha! Since they had pupated, they no longer required any food so I brought them inside and kept them in a jar out of direct sunlight. Last night I noticed one had emerged. It is a silver spotted tiger moth. I turned it loose after a couple of quick photos.
Throughout the many weeks of observation I noted the numbers in my trees decreasing in irregular spurts. I suspect many were devoured by birds. In fact, I think my two were the only ones that made it to adulthood out of perhaps hundreds.
This article appears in Best of Humboldt 2016.
How long did it take for them to emerge as adults once they had pupated?
When you brought the cocoon inside, did you just put the cocoons in the bottom of a mason jar? Was that enough space for the moth to dry its wings appropriately? Did you provide anything for it to climb and hang from?