Proceedings: Animal Sciences

, Volume 97, Issue 1, pp 79–87 | Cite as

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

  • R Ramachandran


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.


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


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  1. Altmann P L and Dittmer D S 1975Biology Data Book Volume 3 (Bethesda: Federation of American Societies for experimental biology)Google Scholar
  2. Bernays E A, Cook A G and Padgham D E 1976 A club-shaped hair found on the first-instar nymphs ofSchistocerca gregaria;Physiol. Entomol. 1 3–13CrossRefGoogle Scholar
  3. Jenson M and Weis-Fogh T 1962 Biology and physics of locust flight, V. Strength and elasticity of locust cuticle;Philos. Trans. R. Soc. London B245 137–169CrossRefGoogle Scholar
  4. Ramachandran R 1987a Influence of host-plants on the wind dispersal and the survival of an Australian geometrid caterpillar;Entomol. Exp. Appl. 45 (in press)Google Scholar
  5. Ramachandran R 1987b Experiments on the responses of the larval stages of the geometrid mothEctropis excursaria to light and gravity;Entomol. Exp. Appl. (in press)Google Scholar
  6. Reynolds S E 1980 Integration of behaviour and physiology in ecdysis;Adv. Insect Physiol. 15 475–495CrossRefGoogle Scholar
  7. Sabersky R H, Acosta A J and Hauptmann E G 1971Fluid flow, a first course in fluid mechanics (Macmillan Publishing Co., Inc.)Google Scholar
  8. Sabersky R H, Acosta A J and Hautpmann E G 1971 Fluid flow, a first course in fluid mechanics (Macmillan Pub. Co. Inc.) pp 519Google Scholar
  9. Sandeman D C 1976 Spatial equilibrium in the arthropods; inStructure and function of proprioceptors in the invertebrates (ed.) P J Mill (London: Chapman and Hall) p 519Google Scholar
  10. Tautz J 1977 Reception of medium vibration by thoracical hairs of caterpillar ofBarathra brassicae L. (Lepidoptera, Noctuidae). I. Mechanical properties of the receptor hairs;J. Comp. Physiol. 118 13–31CrossRefGoogle Scholar

Copyright information

© Indian Academy of Sciences 1987

Authors and Affiliations

  • R Ramachandran
    • 1
  1. 1.Waite Agricultural Research InstituteGlen Osmond

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