 Lilacs are used as food plants by the larvae of some Lepidoptera species including copper underwing, scalloped oak and Svensson's copper underwing.They are small trees, ranging in size from tall, with stems up to diameter.The leaves are opposite (occasionally in whorls of three) in arrangement, and their shape is simple and heart-shaped to broad lanceolate in most species, but pinnate in a few species (e.g.