Blackheaded Ash Sawfly – Tethida cordigera

Blackheaded Ash Sawfly   Scientific Name:  Tethida cordigera (Tethida barda) Common Name:  Blackhead ash sawfly Appearance:  The Blackhead ash sawfly ranges in size from 8 mm in size. The adults are deep black with bright red markings, especially near the thorax. It has pale caterpillar-like larvae, which are usually greenish-white or yellowish-white. Not only does it have segments throughout its body, but it is also hairless. The larva may grow up to 19 mm long. Host Plants or Food: Blackhead ash sawfly mainly feeds on ash Fraxinus, chewing on its foliage for its nutrition. Territory: Throughout North America Mode of Damage:  Young larva chew holes in the leaves while skeletonizing the whole tree. Prolonged leaf chewing may cause premature leaf dropping as well. Habits and Life History: Blackhead ash sawfly is commonly found in deciduous forests with ash trees. Mostly young trees, especially those of ornamental plants, are at a higher risk of infestation. Female sawflies cut slits on ash leaves and lay eggs in clusters on the outer margin of the leaves, giving rise to the first larval instar. The larva feeds on the leaves by chewing holes in them and continues growing. When it is ready to pupate, it falls to the ground, builds itself a cocoon made of soil particles, and stays in it until it turns into an adult. It only produces one generation per year.