IPA: /ˈɡrʌbˌwɜːrm/
KK: /grʌbˌwɜrm/
A young stage of an insect, especially a beetle, that is often found in soil or decaying matter and is usually soft and white or yellowish in color.
The gardener found several grubworms in the soil while preparing the garden bed.
Grubworm is formed from "grub" (from Old English *grubban*, meaning to dig or burrow) and "worm" (from Old English *wyrm*, meaning serpent or worm). The term refers to a larval stage of an insect that is often found burrowing in the ground, resembling a worm.
Think of 'grubbing' in the ground, which connects to the idea of a 'worm' that digs or burrows — that's why a grubworm is a type of burrowing insect.
No commonly confused words.