English for beekeepers

Ocelli: tiny bee eyes

A newly emerged mason bee peeks from its nesting tube. Rusty Burlew

Ocelli (singular: ocellus) are simple eyes with a single lens. This type of eye does not form an image but acts as a photoreceptor, detecting changes in light intensity and direction.

Many arthropods have these small photoreceptors. They are especially common in arthropods that fly—such as bees. Bees have three of them on the crown of their head–centered between the large compound eyes and looking like shiny black dots.

Experiments have shown that photoreceptors help honey bees to navigate at flight speeds. The detection of light overhead helps them navigate and helps them tell up from down. Bees with full sight (all five eyes) were found to be much more cautious and tended to decelerate more quickly than bees whose ocelli were covered[1].

The ocelli are the three tiny dots atop this mason bee's head.
The ocelli are the three tiny dots atop this mason bee’s head. © Rusty Burlew.

[1] Kastberger, G. 1990. The ocelli control flight course in honeybees. Physiological Entomology 15(3):337-346.

1 Comment

  • Ufda! Covering them?! That would ne like covering your one eye. Duh! Depth perception is off, peripheral vision is off, just no bueno. Pretty neat to have 5 eyes though!

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