Borers

21 clues
Augers
Weevils
Drillers.
Iris pests
Corn pests
Plant pests
Woodpeckers
Moles, e.g.
Orchard menaces
Shipworms, e.g.
Damaging insects
Destructive bugs
Tunneling machines
Termites and drills
They're penetrating
Destructive beetles
Destructive insects
Wood-damaging insects
Farmers' bêtes noires
Bugs that live in trees
Insects found in trunks
Similar answers:
Aalborg
Abasers
Abaters
Abcmurders
Abetters
Abiders
Ablepersonality
Abners
Abnersingleday
Abombers
Abor
Aboral
Aborally
Aborc
Abord
Abordo
Abore
Aboreis
Aboreisa
Aboriginal