 Many fungi can serve as source of food for insect larvae , whereas most insects eat fungi only occasionally . Still , a whole range of insect species specialize on fungi . These animals are mainly beetle larvae , especially hairy fungus beetles ( Mycetophagidae ) , rove beetles ( Staphylinidae ) , and true flies ( Diptera ) . Milk caps are especially attractive for true flies , while beetle larvae are comparatively rarer . The most common insects found on the fungus are Mycetophilidae and Phoridae larvae , which populate even the youngest fruit bodies . Also relatively common on mature or overaged fruit bodies are Drosophilidae and Psychodidae . Species from the section Deliciosi are often infested by Diptera larvae . 
