For information regarding Stemma in textual analysis, see Stemmatics

For "stoma" or "stomata," gas exchange pores on plant leaves, see Stoma.

Stemmata are located on the sides of the head of many insect larvae. They are also called lateral ocelli. Caterpillars have six ocelli on each side of their heads, while others such as the nicrophorine larvae have only a single ocellus on each side of their heads.

As the larva develops and matures into an adult insect, the stemmata either are replaced by a more complex visual organ, such as a compound eye, or they become an internal component of that organ.