SIGHT — FIELDWORK AND EXPERIMENTS 5I 



As to food for captive chameleons : an assortment of insects 

 secured by means of a sweep net will provide some variations 

 of diet, while grasshoppers, moths, cabbage white butterflies, 

 and craneflies will be taken freely. Blow-flies can be bred 

 for feeding, but these are not so nutritious as wild caught 

 insects. Some — but not all — chameleons will take meal- 

 worms, but they will seldom feed from a dish. Each meal- 

 worm offered must be lightly attached to a wire and pre- 

 sented so that it will wriggle and attract attention. This is a 

 slow and often time-wasting performance, and the time spent 

 could be more usefully employed in catching insects in fields 

 or hedgerows. 



To return to the use of the eyes in other, more usual kinds 

 of lizards, the British Viviparous or Common Lizard is the 

 easiest to obtain for it is widely distributed and can be caught 

 in the hand once a little practice has been gained. The 

 British Sand Lizard is another species which can be used for 

 close observations, but as it is extremely local in distribution 

 over-collecting must be avoided. It is perhaps better to buy 

 one or two Continental Sand Lizards from a dealer; these 

 will do just as well as our own species. Other lizards suitable 

 for observations under captive conditions are Wall Lizards 

 and Green Lizards. Both these may be bought from dealers 

 during the spring and summer months. 



Whichever kind is chosen it is as well to give varied insect 

 food obtained by sweeping; mealworms are excellent as a 

 stand-by but as they have to be confined in a dish from which 

 they cannot escape they are less useful as tests for feeding 

 experiments than moths, smooth caterpillars, grasshoppers 

 and spiders, all of which will move freely around the vivarium 

 without burying themselves as mealworms do. 



All lizards mentioned will be found to have the most 

 amazingly acute eyesight for moving prey; and compared 

 with some reptiles they certainly have reasonably long sight. 

 I have seen a Green Lizard detect very slight movement in a 

 caterpillar from a distance of four feet. The speed with which 

 these lizards will cover the distance between them and their 

 intended victim is surprising to those who have not watched it 

 take place, and the sureness with which the insect or spider will 

 be seized shows clearly that change of focus is extremely rapid. 



