TROPISMS AND SENSE ORGANS OF LEPIDOPTERA 



By N. E. McIndoo 



senior entomologist, deciduous-fruit insect investigations, bureau of 

 entomology, u. s. department of agriculture 



CONTENTS 



PAGE 



Introduction 2 



A. Tropisins 2 



I. Phototaxis 3 



1. Review of literature : 3 



(a) Definitions and problems in the study of light reactions... 3 



(b) Are light reactions adaptive ? 4 



(c) Is orientation accomplished by selection of trial movements? 5 



(d) How do light rays bring about orientation? 5 



(e) Do circus movements support Loeb's theory? 5 



(f ) What wave lengths stimulate insects most? 6 



(g) Light traps are not yet considered successful 9 



2. Phototactic experiments on codling-moth larvae 10 



II. Chemotaxis 14 



1. Review of literature 14 



2. Chemotactic experiments on codling-moth larvae 17 



III. Geotaxis 19 



1. Review of literature 19 



2. Geotactic experiments on codling-moth larvae 20 



IV. Thigmotaxis 21 



1. Review of literature 21 



2. Thigmotactic experiments on codling-moth larvae 22 



B. Tropic receptors 22 



I. Photoreceptors 23 



II. Chemoreceptors 24 



1. So-called olfactory organs 24 



(a) Antennal organs 24 



(b) Olfactory pores 27 



2. So-called taste organs 35 



III. Audireceptors 39 



1. Tympanic organs 41 



2. Chordotonal organs 41 



3. Johnston organs 42 



4. Auditory hairs 44 



IV. Thigmoreceptors 45 



I. Tactile organs 45 



V. Georeceptors 46 



I. Balancing organs 46 



VI. Other receptors 47 



C. Scent-producing organs 48 



Summary and discussion 51 



Literature cited 53 



Smithsonian Miscellaneous Collections, Vol. 81, No. 10 



I 



