Eyes : Each mole cricket has a pair of large eyes, called compound
eyes. Each also has a pair of small eyes, called ocelli at the top of the head. The length of the ocelli (from front to rear, called ocellar length), the distance between them (called inter-ocellar distance), the shape of the ocelli, and the distance from each ocellus to the compound eye on the same side of the head (called ocellar-ocular length), differentiate the three Gryllotalpa remaining species as follows:
In the European mole cricket the ocelli are nearly circular, and the the ocellar-ocular distance is greater than the ocellar length. In the knife and oriental mole crickets, the ocelli are elliptical, and the ocellar-ocular distance is less than the ocellar length.
In the knife mole cricket the inter-ocellar distance is less than the ocellar length, whereas in the oriental mole cricket the inter-ocellar distance is greater than the ocellar length.