Third stage larvae develop into their fourth and last stage days after being ingested by their final host. In fourth stage larvae, the three lip segments are still present, but the dorsal segment has grown to be larger than the ventrolateral ones, and the boring tooth is no longer present within them. At the rear end, the mucron is replaced by a cone-shaped protrusion with small globular structures on it, and the previously irregular striations and indents on the outer surface of the organism become regularly patterned. At this stage, female larvae begin to develop reproductive organs at the center of their bodies, including internal genitalia, uteri and surrounding papillae.
