636 C. B. HARDENBERG. 



of South African Heterocera are very few, and such as 

 exist are usually based on the last instar and are confined to 

 general statements as to size and colour-pattern. No detailed, 

 careful descriptions are available. This is greatly to be 

 regretted, both from an economic and a scientific point of 

 view. 



Let us consider the question first from the economic side. It 

 is almost without exception the caterpillar, not the adult insect, 

 which causes the damage, and it is this stage of the insect's 

 life which is sent to the entomologist together with the 

 complaint about its depredations. In the absence of reliable 

 descriptions (and, owing to the scarcity of preserved larval 

 skins, careful comparison with known specimens of which the 

 adults have been bred is usually impossible), it is necessary 

 to breed the insect to its adult stage before its identity can be 

 ascertained without a doubt. Anyone who has tried to rear 

 such larvae, sent in from a distance, sometimes without the 

 food-plant and in a closed box, realises the comparatively 

 small chance of success. What with the parasites from 

 which such specimens often suffer, the weakly and often 

 diseased condition of the larvee, the paucity of material and 

 the artificial conditions under which it has to be reared, not 

 to mention an often compulsory change of food-plant, the 

 specimens either die before pupation, or, if a pupa is formed 

 it is often so lacking in vitality that the moth does not emerge. 

 Determination of the species in question then depends entirely 

 on the examination of the pre-adult stages. 



With the state of our present knowledge (or rather lack of 

 it) of South African caterpillars, there are thus many chances 

 of wrong determination, even in cases of some of the most 

 common and widely-known pests. As an instance I may 

 mention that a larva, found hibernating under the bark of a 

 pear-tree, was at once declared by one of our most experienced 

 entomologists to be that of the Codlin Moth, while subsequent 

 rearing of the specimens by the writer proved it to be an 

 entirely different species. Also, the moths of two different 

 species may look extremely alike, except to the Micro-Lepi- 



