Birch Sawfly – Arge pectoralis

Birch Sawfly   Scientific Name:  Arge pectoralis Common Name: Birch sawfly Appearance:  Birch sawfly is a blue-black insect with a few white markings on its legs. The size varies from 9 to 11 mm. Its thorax also has a crimson part near the head. It has a yellow-orange larva with black spots on the upper side. Host Plants or Food: Birch sawflies mainly feed on yellow, white, and grey birch trees, hence called birch sawflies. However, it may also have hazelnut and willow trees as its host plants. Territory: Throughout North America Mode of Damage:  It is exclusively a leaf chewer and feeds on the foliage of its host plants. The larva is capable of defoliating the entire leaf and leaves behind only the midrib. Habits and Life History: Birch sawfly is commonly found in woody areas with birch trees. The females make a slit near the margin of the leaves and lay the eggs in it. The larva hatches out of the eggs and readily feeds on the leaves for some time. After that, it falls to the ground, makes a cocoon out of silk threads and pupates in it. Since it cannot survive cold, it pupates through the winter season. It only has one generation per year. Adult sawflies appear during June and July, giving rise to the larva in July and September.