Dugbogs are swamp dwelling creatures that resemble rotting logs. Their main source of food is mandrakes often killing the plants while they're still buried in the soil. In Harry Potter and the Silver Snitch, The third years are tasked with protecting Sprout's Mandrake crop from Dugbogs. Gardeners find a Dugbog has been at their mandrakes when they pull up dead and bloody plants.
Dugbogs are the subject of the short rhyme “Dugbogs and Bugdogs.”