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INSECT PESTS OF VARIOUS MINOR CROPS AND FRUIT TREES IN 



MAURITIUS. 



By D. d'Emmerez de Charmoy, 

 Entomologist to the Department of Agriculture, 



and S. Gebert. 

 First Scientific Assistant, Division of Biology. 



The following paper deals with insect pests of various minor crops and fruit 

 trees in the Colony of Mauritius. The damage caused by most of the pests dealt 

 with is often not very apparent, as many of these crops are not grown extensively, 

 and have not been the object of any special investigation up to the present. If 

 extensive cultivation of any of these should be undertaken, it is clear that there 

 might be created a new environment favourable to increase of the insects, and that 

 the pest problem would then have to be dealt with seriously. Our knowledge of 

 these pests is very deficient, as their life-history and habits have never been studied 

 in detail locally. It is also quite probable that extended cultivation may bring 

 to light many potential pests which at present escape our attention. 



The crops dealt with in this paper are all capable of being developed in the future 

 and, for the present, nothing more than a mere enumeration of the pests for which 

 they serve as hosts can be made, except in a few particular cases. These brief notes 

 should only be considered as a preliminary study which will serve as a guide, as 

 well as a warning, to those who are likely to give more extensive attention to these 

 economic plants. 



Cotton. 



The cotton occurring in the Colony consists merely of a few plants scattered 

 over the island. In former years, as far back as 1847, the plant used to thrive in 

 many localities, where its cultivation was carried out on a moderate scale. The 

 yield and quality of the cotton were good, and no trouble due to insect attack seems 

 to have been experienced. Attempts to grow cotton on a large scale were made 

 in 1911, but owing to various unfavourable conditions, such as bad weather, drought, 

 scarcity of labour, and insect attacks, the enterprise did not succeed. 



The Department of Agriculture, which did not exist then, is now taking up the 

 matter, and it is hoped that a certain extension will be given to cotton growing. 



The enemies of cotton are mainly cosmopolitan, and most of the chief cotton 

 pests that have been recorded in other parts of the world occur here ; the following 

 have so far been noticed :— 



Prodenia litura, F., and Spodoptera mauntia, Boisd. These two species of cut- 

 worms, though not true cotton pests, are nevertheless polyphagous, and therefore 

 likely to prove injurious to cotton. Prodenia litura is the commoner of the two, 

 and proves quite troublesome to garden plants during the hot season. The eggs 

 of this moth are parasitised by a species of Telenonws ; the development of the 

 parasite in the egg of the moth takes 21 days, and the proportion of males to females 

 emerging from the eggs is, on an average, 1 to 3. 



Cosmophila fiava, F. [xanthindyma, Boisd.). The caterpillar feeds on the leaves 

 of cotton. 



