The sense organs of insects present a great variety of forms, giving responses to different types of stimuli. The different kinds of sense organs are distinguished by the nature of the stimulus that acts on the sense organ.  This stimulus may be mechanical, chemical and light stimulus.  The photo stimuli are responded by various types of photoreceptors in animals but in the case of insects it is caused by compound eyes and simple eyes or ocelli. The ocelli are the complex and delicately organised sense organs in insects. Dorsal ocelli are found in adult insects.  The numbers of ocelli in insects differ according to the family and order. The numbers of ocelli present in Gryllodes sigillatus are three, among them two are lateral ocelli and one median ocellus.The orthopteran insect Gryllodes sigillatus has well developed ocelli which are structurally adapted for diurnal and nocturnal activities. All the three are helping in vision like compound eyes by the presence of photoreceptive cells and also undergoing dark adaptation.  The structure of ocelli consists of photoreceptive cells, lens, corneagen layer, retinal cells, rhabdom, pigment, retinual axon   and oceller nerve.

Keywords: Gryllodes sigillatus, insects, lateral ocelli, median ocellus, photoreceptive cells, retinal cells, lens, corneagen layer, retinal cells, rhabdom, pigment, retinual axon and oceller nerve

| DOI: 10.17148/ IARJSET.2019.61105