What injection uses holes this large?

[Basswood]

I was making a PGR application today to a Hickory when I came across what I assume is injection sites. I’ve never seen some this large and can’t imagine why they would be at maybe 1/2”. Any one have any info? They were about every 6-10” if I had to guess off of memory.

 

[Serf Life]

Guessing homeowner applied acetate capsules. I’ve been seeing similar treatments around here for browntail moth.

 

[Basswood]

Interesting. I’m not familiar with that one nor is that a pest we deal with down here. I hear they hurt pretty good.