• A club-shaped sensory hair on the first instarEctropis excursaria (Lepidoptera: Geometridae) and its role in the behaviour of the caterpillars

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    • Keywords


      Club-shaped hair; first instar; morphology; distribution; orientation; spring constant; torque; deflection; gravity receptors

    • Abstract


      A unique club-shaped hair on the first instars of an Australian geometrid caterpillar is described. The sensory hairs occur on the body segments and is absent on the head and the last abdominal segment. These hairs have different orientations and are replaced by filiform hairs after the first moult. Regression lines describing the movement of hairs of different orientations in relation to a force is presented. With these results the deflection in the sensory hair due to gravity when the caterpillar is on a vertical plane was calculated. These calculations suggest that the hairs may not function as gravity receptors. The possible role of these hairs in the behaviour of caterpillars is discussed.

    • Author Affiliations


      R Ramachandran1 2

      1. Waite Agricultural Research Institute, Glen Osmond, South Australia - 5064
      2. Entomology Section, National Chemical Laboratory, Pune - 411 008, India
    • Dates


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