SOME SUGGESTIONS FOR THE STUDY OF INSECTS. 159 



Pupa or Chrysalis Stage. In this stage our insect does 

 not feed or move about, but lies quite passively (Fig. 58) . 

 This is the almost universal rule (but we may note in 

 passing the pupae of gnats and some other insects which 

 retain their powers of locomotion, but do not feed). Yet 

 we know that under the stiff outer shell important changes 

 are going on. There is a breaking down of the caterpillar 

 organs and a building up of new ones. And when this is 

 completed there emerges from the cuticle of the pupa, 

 which is cast aside, the winged adult insect in 

 the present instance, a beautiful moth. 



At this point it is well to summarise the out- 

 standing facts. 



We have seen that caterpillars are only a 

 stage in a life history. When young animals 

 which feed themselves are unlike their parents 

 in general habits and structure, they are usually 

 termed larvae. Caterpillars are larvae. 



Their life consists in feeding and growing. 



The pupa is a stage in which preparation 

 is made for the adult condition. It exhibits neither 

 feeding nor growth. The teacher should inquire the mean- 

 ing of the terms pupa and chrysalis. If possible the 

 pupae of the small tortoise-shell butterfly (Vanessa urticae) 

 should be obtained (its caterpillar feeds upon the nettle) 

 in order to show the appropriateness of the latter term 

 (Chruseos = golden). Many of the pupae of this common 

 insect exhibit a remarkably fine metallic lustre. 



It is desirable that some comparisons be made of 

 different common caterpillars, e.g. as regards the number 

 of pro-legs; the colour in relation to that of the food 

 plant, whether resembling it, or conspicuous upon it; 

 and some observational work might be attempted out of 

 doors with a view to discovering what common types are 

 taken or rejected by birds. 



The winged insect is considered in the following lesson. 



