The term 'young insect' can be described by the crossword solution 'LARVA' which is a 5 letter word. LARVA is the stage of an insect's life cycle between egg and adult. It is characterized by a dramatic change in form, size, and habits. Larvae are typically worm-like in appearance and feed on plants or other food sources. They are usually found in aquatic environments, but can also be found in terrestrial habitats.