142 



CHAPTER IX 



Because of theii economic importance the borers have been studied in 

 great detail. As they occur in Java reference may be made to Kruger and 

 Van Deventer, Maxwell Lefroy has described the West Indian borer^^ 

 and the borers of British India.^^ That of Mauritius has been described 

 by Bojer^^ as Procerus saccharifagus , and by Delteil as Toririx saccharifaga, 

 and that of New South Wales by Ohff.^^ A full description of Diatrcea 

 in the southern part of the United States has been given by Howard. Here 

 it also appears as a corn stalk borer. 



The following life history of the West Indian borer is due to Maxwell 

 Lefroy : — ^^ 



" .... the eggs are flattened, oval and slightly convex, about i /25th inch 

 in length ; they are laid in clusters on the leaf of the cane, the number being very 

 variable, lying between 4 and 57, and being generally from 10 to 30. The eggs 

 when fresh are light yellow ; in 36 hours a tinge of orange appears, and eventually 

 they turn orange brown ; in the final stage the centre of the egg becomes black. 

 If the eggs are laid on young cane, the part attacked is the axil of the leat or the leaf 

 itself ; in the case of older cane, the part attacked is the joint, the caterpillar 

 eating its way into the cane from which it eventually emerges in from 30 to 35 days. 

 The period of pupation which takes place inside the cane is six days, after which the 

 perfect insect emerges. The moth is inactive by day, and, only living 4 days, lays 

 in that^time from 100 to 300 eggs." ^ j 



tMM 



Fig. 43 



Fig 



Leaf-eating Caterpillars. — Occasionally cane-growing districts are visited 

 by great numbers of leaf-eating caterpillars, which appear suddenly and as 

 suddenly disappear. Most of these are the larvae of noctuid moths, the 

 most notorious being the " army worm," Cirphis (Leucania) unipuncta, 

 the " grass aimy worm," Spodoptera mauriiia, and various cut worms 

 belonging to Agrotis and allied genera. Very many of these pests are known, 

 Swezey^^ having observed thirty-five species in the Hawaiian Islands alone. 



