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The Bug Geek
Insects. Doing Science. Other awesome, geeky stuff.
A sticky situation
Posted by on March 3, 2010
Alright, I have a little mystery for y’all. I found this:
on the side of a fairly young spruce tree. It’s a wad of hardened resin about the size of my palm, with holes in it. I tend to assume holes=bugs, so I got out my knife and started poking at it.
While I didn’t find anything IN the sap, I found this UNDER it:
It looks like a Lep methinks. It was about half an inch long. It seemed to me that there was very small, round, frass-like debris under the resin, but sometimes I imagine bug-ness where there is none. The wood of the tree directly beneath it was very soft, almost spongy.
Um…10 points to anyone who thinks they know what’s going on here. Bonus points for ACTUALLY knowing what’s going on.
The Bug Geek 
Although I’ve never seen the larva, I’m thinking that this is the pitch mass borer (Synanthedon pini, family Sesiidae) based on that characteristic pitch mass. Larvae apparently tunnel underneath the bark in pine and spruce, feeding on the resin that is exuded by the damaged tissues.
Ohh, a Sesiid! They’re cool.
I found some images of S. pini larvae, and it doesn’t look at all like the critter I found. I suspect the little guy just wandered up underneath the pitch because it made a good hidey-hole.