1) yes 2) several seasons now. Have had pest control companies out with no results. 3) yes so far it is contained to a spot outside the garage doors. Outdoors. I have cleaned up area completely several times. Mortar dust continues to accumulate.
I heard back from Jeff Hahn in regards to the insect issue. I will paste his response below:
I have had a chance to talk to my colleague. He agrees that insects are not causing this damage, they are not capable of it. He speculates that it is possible that mortar was not mixed properly which could result in it crumbling now.
When I first looked at the pictures of the insects, I identified the first one as a small moth. Looking at it a second time, I realize it is actually a scaly-winged barklouse. This is important because barklice are associated with damp conditions. The second insect picture looked like it could be a springtail which is also associated with a damp environment. It is possible that the area where the problem is occurring is damper and could be contributing to the damage.
Ultimately, they need a builder to look at the problem and see if they can determine the problem and a solution.
This work is supported in part by New Technologies for Ag Extension grant no. 2020-41595-30123 from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.