446 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



Hampson, are undoubtedly the most serious pests of cane. The im- 

 portance of the smaller moth borer is recognized by the planters 

 and managers, and most strenuous measures have been adopted for 

 its control. On practically every estate there are gangs of boys, 

 sometimes as many as fifty in a gang, who do nothing else the year 

 round but cut out the dead hearts which have been caused in the 

 young cane shoots by the Diatrcea larvae. The boys receive 6 cents 

 per 100 for the larvae and every effort is made to make the work 

 thorough and systematic. There is a tacit understanding between 

 the boys, however, that the collection of 700 is a fair day's work 

 (and this represents more than a fair day's wage for a man) and 

 they make no particular effort to collect more than about that 

 number. It shows how serious the pest is, that the boys have no 

 difficulty in collecting this number of larvae day after day. The first 

 impression one receives on going into a field of cane ready to be cut, 

 is what an enormous amount of damaged cane is present. It is not 

 at all difficult to find stalks with Diatrcea holes and burrows in every 

 internode, and it is practically impossible to find a single stalk of 

 uninjured cane. For the ordinary varieties of cane this would mean 

 that there would be practically nothing left worth grinding, but in 

 Demerara, this problem has been met, though not solved, by the 

 almost universal use of a local seedling cane, Demerara, 625. Although 

 not highly resistant to Diatrcea, it is more so than the older varieties 

 and it is a valuable cane to plant for that reason, despite its low sucrose 

 content. 



The problem of controlling Diatrcea is most seriously complicated 

 in Demerara by the wet and dry seasons. There are always two and 

 sometimes four wet seasons, and of course as many dry. Cane is 

 c»t towards the end of each dry season and seed cane will be planted 

 at each wet season. As it takes from a year to eighteen months for 

 the maturing of a crop, it can readily be seen that cane in all stages 

 of growth is present on a single estate at all times. This means that 

 there is always present, as partly or fully grown cane, a continuous 

 and abundant source of re-infestation of the fields of young cane 

 from which all the dead hearts have been cut out. Moths will fly 

 out a hundred yards or more from the older cane, and more especially 

 from cane that has been cut, depositing eggs on the young cane from 

 which all the dead hearts have just been cut out, and in two or three 

 weeks, the infestation will be as heavy as though no control had been 

 attempted. 



In addition to the attempted control of Diatrcea by artificial means, 

 the numbers of the pest are still further greatly reduced by parasites, 

 four of which are present in Demerara. Two are parasites of the egg 



