Burdock bore hole and 'waste'

Burdock bore hole and 'waste'

Observation - Burdock bore hole and 'waste' - UK and Ireland. Description: Spotted what looks like frass in a Burdock leaf, then saw a hole in the main stem above. Any ideas as to what could have caused this? Thanks!

Spotted what looks like frass in a Burdock leaf, then saw a hole in the main stem above. Any ideas as to what could have caused this? Thanks!