SOUTH AFRICAN CATERI'ILLARS 177 



forms are represeutecl and tliat these must be accom- 

 panied by the immature stages, food-plants, etc. 



And there is still another incentive for tlie collector 

 to look for the larva3 in the field. With the ordinary 

 methods of collecting, be it with the net or at light, many 

 speMmens are either damaged or such as are captured 

 are found in an imperfect condition, and many collec- 

 tions are rendered unsightly by the presence of such 

 broken and rubbed specimens. Collectors therefore have 

 realised that the only sure way to obtain specimens in 

 their pristine beauty is to breed them, and many are now 

 making special arrangements for doing so. And Avhen 

 the object is to obtain long series of a certain species for 

 the study of individual variation, this can only be accom- 

 plished by breeding. 



It is principally through the efforts of so many of the 

 older collectors, w^ho wished to obtain perfect specimens, 

 that a gTeat portion of the caterpillars of the Rhopalo- 

 cera and of the larger moths have become known and 

 have been figured and described. 



Lastly, there are many species which cannot be ob- 

 tained in any other way, as they are never seen at the 

 time when net collecting is being done and are not at- 

 tracted to the light in the evenings. Such are the majority 

 of the Psychidac and miany Tineidae. While the larvjp 

 of these may be very plentiful, the adults are rarely found 

 in the collections, and breeding is the only method by 

 Avhich these can be secured. Many species which hitherto 

 have been considered great rarefies can thus be obtained 

 in number. 



(h) The Economic Value of the Study of Caterpillars: 

 — Considered from the standpoint of the economic ento- 

 mologist, the larval stage is usually the most, if not the 

 only important one in the case of injurious insects. This 

 is especially true in the case of Lepidoptera. The farmer 

 or fruitgrower whose crops are being destroyed, or the 

 forester whose plantations are being defoliated, usually 

 notices only the caterpillars, and in this form the insect 



