"Suillus luteus" fruit bodies are sometimes infested with larvae, though not nearly as often as "S. granulatus" or "B. edulis". Damage from maggots is much more common in warmer months, and rare late in the season with cooler weather. In a Finnish study, researchers found that 70–95% of fruit bodies collected from typical forest habitats were infested with larvae; the most common species were the flies "Mycetophila fungorum", "Pegomya deprimata", and "Pegohylemyia silvatica". In contrast, other studies have shown that fruit bodies collected from pine plantations are relatively free of larvae. The fungus produces microscopic crystals of oxalic acid at the surface of its hyphae, a feature that is thought to help deter grazing by the springtail species "Folsomia candida".