light green with black spots and head of birch sawfly (cimbex femoratus) false caterpillars eat alder leaves

alder animal animals background black borer bug butterfly caterpillar caterpillars close closeup colors cudweed day depredator development eat entomology fauna flora forest garden green hairy head heard insect insects larva larvae leaf leaves light natural nature outdoor season sports spots spring stage summer tree wild wildlife wood yellow zoology cimbex femoratus