VPA 221: Veterinary Entomology and Acarology (1+1)

BLACK FLIES - LARVAE

• Whitish or greenish in colour
• 6-9 larval stages, mature larva is 4-12 mm long, elongate, Indian club or hour glass shaped body
• The posterior end of the abdomen and thorax are broader than the anterior part of the abdomen
• Distinct sclerotized head, black with a pair of simple eyes
• Prominent pair of cephalic fans (labral fans) which aid filter feeding by the larvae
• Larvae are anchored to the rocks  by means of the thoracic and abdominal prolegs, these are provided with a circlet of hooks which enables adhesion with the substrate
• The larva also produces silk with the help of the silk glands and the hooks on prolegs enmesh with the silk pad produced by the silk glands
• Typical movement of the larvae over the substrate is by the looping movement, especially in areas where there is threat of the fast flowing water removing the larvae from its original habitat
• Mature larva is recognized by a gill spot on either side of the thorax
• Larva is also provided with 3 pairs of retractable anal gills
• Larvae are carnivorous and predacious on aquatic organisms
• They are phoretic on crabs or any fast moving objects