The scarlet lily beetle, or red / leaf lily beetle, is a leaf beetle that eats the leaves, stem, buds and flower of lilies, fritillaries and other members of the family Liliaceae. They mainly lay their eggs on Lilium and Fritillaria species. It is now a pest in most temperate climates where lilies are cultivated. Not only are the eggs laid underneath the leaf to stay hidden but they are also covered with a thick sticky brown substance for further protection. As larvae, they use their own frass (excrement) to make a protective shield, allowing protection from the sun and predators. However, the fecal shield is not an adequate protection against parasites - it actually acts as a chemical cue for the parasites to locate the larvae. An adult that senses danger displays a defense mechanism, thanatosis, becoming motionless, folding up its appendages and falling with its black under surface facing up, thereby helping it camouflage with the ground to get away. If unable to escape, they are also able to ‘squeak’, by rubbing two parts of their body together, which may be used to startle the attacker. This process is known as stridulation and could even shock a bird or any other predator that may attack the lily leaf beetle
Scarlet lily beetle is indigenous to parts of Europe and Asia. It is thought to have been introduced to North America through the import of plant bulbs around 1945. First spotted in Montreal, it has spread throughout Canada and the eastern United States within decades. It has also become an invasive alien insect in the United Kingdom, where it has established itself after its introduction in 1943. It has since spread from Surrey to as far north as Glasgow.