Altered Regeneration

Stick Insects That Lose an Antenna Sometimes Regenerate a Leg.
Top: Antennae of Stick Insect. If antennae of an immature are cut on the dotted line, a leg may be regenerated during the next molt
Bottom: Stick Insect That Lost Its Antennae in the Previous Stage Has Regenerated Legs
Image: Volker Dürr

For over 100 years the derivation of insect antennae from the ancestral leg has been known. In 1914, Schmidt-Jensen studied regeneration in the stick insect and reported that sometimes after the molt, a leg appeared where an antenna should appear. We now know more about the genes involved in the regulation of appendages. These genes determine whether an appendage will be a leg, a mouthpart or an antenna.

If the antennae are cut through the pedicel, the genes that produce an antennae during the molt are not properly expressed resulting in a stick insect with legs on its head.

*Schmidt-Jensen, H.O., 1914. Homoetic regeneration of the antennae in a phasmid or walking-stick. Smithson. Rep. 1914, 523–536.