Egg and early-instar morphology of Lymantria juglandis (Lepidoptera: Erebidae: Lymantriinae): Insights into its functional implications

Lymantria juglandis Chao, 1984 is an important arboreal defoliator, yet the immature morphology has remained poorly documented despite its ecological importance. In this study, the egg and early larval stages of L. juglandis were described using light microscopy and scanning electron microscopy to clarify diagnostic characters and developmental adaptations. The hemispherical egg exhibits a finely reticulated chorion composed of contiguous polygonal cells with numerous aeropyles at ridge intersections. First-instar larvae bear dense verrucae and two distinct types of setae: elongated barbed setae with extended socket bases and spiniform setae with a subbasal bulbous process, features likely functioning in mechanical and chemical defense. Crochet number increases progressively during larval development, from four in the first instar to ∼12 in the second and ∼32 with a median process in the third, reflecting enhanced grasping ability and substrate adaptation. These morphological features provide new diagnostic evidence for Lymantria and advance comparative and functional interpretations of early developmental stages within Lymantriinae.