In cockroach, eye consists of visual units called
Ostia
Ommatidia
Gonapophyses
Spiracles
Eyes of cockroach -
Head shows two compund eyes which are present on dorso-lateral sides. Eyes are considered as the appendages of 1st head segment. The top of the head between the two compound eyes is called vertex.
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The primary visual organ in most adult insects is the compound eye. Compoundeyes consist of repeating units called ommatidia, which together form the retina