772 



LIGHT AND LIFE 



TABLE 1 

 The Orders of Insects in Which There Is Evidence for Color Vision 



Order Genus Method and Reference 



Odonata 



(dragonflies) 



Blattaria 



(cockroaches) 



Coleoptera 

 (beetles) 



Hymenoptera 

 (bees, wasps, 

 ants, etc.) 



Diptera 



(flies) 



Lepidoptera 

 (moths and 

 butterflies) 



Aeshna (nymphs) 



Libellula 

 Periplanela 



Chrysomela, Agelastica, 



Geolrupes 

 Notonecta 

 Apis 



Eristalis 

 Fannia 

 Drosophila 

 Calliphora 

 21 genera 



training (34) 

 electrophysiological (40a) 



electrophysiological (56, 57, 58, 59) 



optomotor (48) 



optomotor (45) 



training (e.g., 16, 35, 4, 29, 9, 36) 



electrophysiological (20) 



training (32) 

 optomotor (48) 

 observation of behavior (24) 

 electrophysiological (2, 58, 59) 



training (30) 

 optomotor (48) 



papers or monochromatic lights under conditions where one is con- 

 fident that chscriminations are based on wavelength and not on bright- 

 ness, odor, or some other property of the test object. Second, many 

 insects have a characteristic reaction — the optomotor response — to 

 movement of vertical stripes in the visual field. W^hen stripes of a 

 given color alternate with gray, a shade of gray can generally be 

 found such that movement of the stripes does not elicit a reaction 

 from the insect; the gray and colored stripes are then said to be of 

 equal "brightness." It has been observed, however, that two alternat- 

 ing colored stripes, each of the same brightness as a given gray, con- 

 tinue to evoke a response from many insects. In general, the more 

 distant are the colors in the spectrum, the stronger is the optomotor 

 reaction. Finally, in several instances electrophysiological observations 

 on compound eyes have indicated the presence of receptors maximally 

 sensitive in different regions of the spectrum. In essence most of this 

 evidence is of the following kind: when two maxima appear in the 

 spectral sensitivity function and it is possible to alter the relative 

 heights of the two peaks by selectively adapting the eye with colored 

 lights, the presence of more than one visual pigment is indicated. 

 Further, if in the same animal different regions of the spectrum evoke 

 qualitatively different retinal action potentials — potentials whose 

 wave forms cannot be matched by any adjustment of the intensity — 

 it is clear that more than one kind of receptor mechanism is present. 

 These and related exjjcriments will be considered more fully below. 



