sawfly larvae in defensive posture eating the edge of a hazel leaf

leaf green nature insect invertebrate plant animal tree wildlife arthropod shrub sawfly larvae defensive posture eating edge hazel animals arch birch black spots caterpillar closeup craesus septentrionalis creepy curl damage deciduous defense defoliation disturbed dusky entomology feeding flat-legged tenthred foliage grey hungry leaves macro margin nematus outdoors parasite pest prolegs raised body shape scare shiny head small wasp yellow