The apparatus was constructed a glass funnel connected to a short piece of rubber tubing at the outlet. Several layers of gauze were laid over a wire mesh at the bottom surface of the funnel. With the outlet closed, the digested solution was poured into the funnel until the fluid level touched the wire mesh. The apparatus was left standing for 30 minutes to allow larvae migrate into the rubber tube. At the end of this period, the fluid containing mainly enriched L3 larvae was released into
a Petri dish. They were morphologically identified using the following criteria: (1) the body is long, thin and delicate; (2) It has two chitinous rods at the anterior end and the cuticle possesses delicate transverse striations; (3) the tail is cone- shaped, slightly curved and pointed.