Plants have morphological and chemical defenses against herbivory. Leaf modification into spines, presence of sharp thorns and spiny leaf margins are some of the morphological defenses. Chemical defense mechanisms include the production of phytoalexins and constitutive compounds by plants. These are the secondary chemical compounds that serve as toxins/ disturb metabolism or normal development of larva or reduce the digestibility of plant. For example, mustard oil from mustard plants, milky sap from milkweed family plants.