Researchers in Australia concerned about the sharp decline of freshwater crocodiles who eat a toxic, invasive toad species have come up with a stomach-churning way for the reptiles to help themselves.

In 1935, native beetles were wreaking havoc on Australia’s sugar cane crops in Queensland. The beetle larvae lived in the soil and chewed on sugarcane roots, stunting growth or killing the plants.

This marsupial carnivore is endangered, mainly because it tries to eat toxic cane toads. Some scientists think they can stave ...