The larva of L. trifolii are unique from those of many other flies in their shape, as the body of L. trifolii larva does not taper at the head end.
The larva are uniform in thickness at both their anterior and posterior ends but additionally have a pair of spiracles at the posterior end.
They do not have legs and are initially clear in color, but gradually become yellow as they mature.

The larval instars are differentiable by the lengths of the body and mouthparts.
The first instar is recognizable by a mean body length of 0.39 mm and a mouthpart length of 0.10 mm.
For the second instar, the mean measurements are 1.00 mm (body) and 0.17 mm (mouth).
For the third instar, the mean measurements are 1.99 mm (body) and 0.25 mm (mouth).
The fourth instar is a non-feeding stage and thus is usually disregarded.
The larva of L. trifolii are unique from those of many other flies in their shape, as the body of L. trifolii larva does not taper at the head end. The larva are uniform in thickness at both their anterior and posterior ends but additionally have a pair of spiracles at the posterior end. They do not have legs and are initially clear in color, but gradually become yellow as they mature.
The larval instars are differentiable by the lengths of the body and mouthparts. The first instar is recognizable by a mean body length of 0.39 mm and a mouthpart length of 0.10 mm. For the second instar, the mean measurements are 1.00 mm (body) and 0.17 mm (mouth). For the third instar, the mean measurements are 1.99 mm (body) and 0.25 mm (mouth). The fourth instar is a non-feeding stage and thus is usually disregarded.
Liriomyza trifolii