184 D. d'emmerez de charmoy and s. gebert. 



It will be seen from this that Sesamia is a very serious pest. In addition to 

 boring the stems it also attacks the cobs. The natural enemies of this moth are 

 four in number. Telenomus sp. is an egg parasite, which has already been mentioned 

 under Prodenia. The life-cycle in the egg of Sesamia is the same as in that of Prodenia. 

 Trichogramma anstralicum, Gir., is another egg parasite. Henicospilus antancarus, 

 Mori., and Stauropodoctonus mauritii, Mori., are both parasitic upon the full-grown 

 caterpillar. 



Pyoceras [Diatraea) sacchariphaga, Boisd., is less common than the former and 

 attacks the plant in the same way. 



Aphis niaidis, Fitch, is sometimes common on the leaves, but is not a regular 

 pest. 



Chloridea obsoleta, F. The caterpillar is often foimd attacking the tender top 

 part of the stem and also the young ears. It frequently feeds on the silks, sometimes 

 destroying them entirely, in which case the ears become barren, and also bores its 

 way into the cob after having fed on the young grain. Many ears are spoiled in 

 this way. 



When maize ears are allowed to remain on the plant until the latter has dried up, 

 the grain is invariably attacked by weevils, Calandra oryzae, L., being the chief pest. 

 Damage is also done by Dinoderus minutus, F. Over 50 per cent, of the grain may 

 be destroyed before storage. These pests, as well as a Tineid moth, also cause serious 

 damage to stored maize if fumigation is not resorted to. Full details concerning 

 these insects wiU be found in Bulletin No. 2 of this Department's Scientific Series 

 (Insects Injurious to Stored Grains in Mauritius). 



Manioc [Manihot utilissima). 



Manioc is another important foodstuff, being largely used for stock. The plant 

 thrives in the hot districts, and gives very good returns. A great many varieties, 

 most of them imported lately by the Department of Agriculture, are growm. There 

 are practically no insect pests of the plant. 



Lachnosterna [Phytalus) smithi, Arrow, is an occasional pest in the infested 

 regions. 



Saissetia heniisphaerica, Targ., is sometimes found on the leaves, but is a minor 

 pest. A species of Chionaspis occurs frequently on the stem. 



Sweet Potato {Ipomoea batatas). 



This tuber is greatly in favour with the poorer classes of the population, and is 

 also an important cattle food. The plant grows well all over the island, the highest 

 yields being obtained in the hotter lowland regions. A great number of varieties 

 are grown, most of which have been imported lately by the Department of Agriculture. 



The chief pest of the foliage is a Pterophorid moth, Trichoptihts leahlbcrgi, Z., 

 the larva of which feeds on the leaves, especially the tender parts and buds, and 

 rolls up in the leaf before pupating. 



Ercta ornatalis, Dup. This Pyralid moth is another leaf pest. 



Herse {Sphinx) convolvidi, L. The caterpillar is occasionally found on the sweet 

 potato, but cannot be regarded as a pest. 



Aspidomorpha obovata, Klug. This Chrysomelid beetle is also an occasional pest, 

 doing no great damage. It lives on various wild species of Ipomoea. 



Cylas formicarius, F., is by far the worst pest. It is exceedingly common whenever 

 sweet potatoes are grown in mounds, and is then responsible for very serious damage. 

 As many as 50 to 100 larvae may be found in a single tuber. The method of planting 

 sweet potatoes in mounds has only recently been adopted, and the resulting looseness 

 of the soil certainly renders the plants more liable to the attacks of this beetle. 



