Mormolyce phyllodes can reach a length of . These beetles possess a flat, leaf-shaped, shiny black or brown body with distinctive violin-shaped translucent
elytra (hence the common name). This characteristic
mimicry protects them against predators, while their flat shaped body allow them to dwell in soil cracks or under the bark and leaves of trees. Head and pronotum are very elongated, with long antennae and the legs are long and slender. The habits of
Mormolyce are not yet very clear, but from the few existing studies it has been determined that their larval habits are completely different from most other
Carabidae: their larvae live in huge (20 to 30 cm wide, or even larger) and very hard bracket fungi, in which they excavate channels and also pupate. After emergence, they create an incredibly small hole, narrower than their own bodies, to escape from their larval chambers, making it difficult to understand how they get out, even "allowing for the softness of its tissues". Their adults – like other Carabidae – are
predatory. For defense purposes, they secrete poisonous
butyric acid. The larvae live in layers of
bracket fungi, genus
Polyporus. Their development lasts 8–9 months, while pupation lasts 8–10 weeks. Adults fly from August to November. ==Distribution and habitat==