INSECT PESTS IN MAURITIUS. 



183 



Although the insects attacking this phmt are not numerous, it is nevertheless 

 useful to record them. 



Pyodenia litum, F., and Spoiloptera mauritia, Boisd. The habits of these cater- 

 pillars have already been mentioned under cotton. The damage done to tobacco 

 seedlings may be very great. 



Coelonia (Sphinx) solani, Boisd. A minor pest. 



Phytometra (Plusia) orichalcea, F., and P. chalcytcs, Esp. These two polyphagous 

 insects feed occasionally on tobacco. A certain amount of damage is caused to 

 seedlings. 



Chloridea obsoleta, F. This moth is here the chief pest. The caterpillars eat into 

 the seed-capsules and often cause great damage ; they are also found on the leaves. 



Thrips sp. Thrips are occasionally found in tobacco flowers, but do no great 

 harm. 



Heterodera radicicola. The roots are sometimes so badly infested with eelwomis 

 as to cause the death of a good many plants. 



Maize. 



Maize is another important food crop and its cultivation is being extended 

 yearly, there being now over 5,000 acres under this crop. Though the hst of pests 

 is not long, appreciable damage is caused, especially to the cobs and seedlings. 



Prodenia litura, ¥., and Spodoptera mauritia, Boisd. These two cutworms damage 

 the seedlings and are occasionally found on the leaves of the mature plant. 



Sesamia vuteria, Stoll. Seedhngs are badly attacked by the caterpiUars of this 

 moth. Its life-history and habits have been worked out and published in a Bulletin 

 on Moth Borers of the Sugar-Cane (Scientific Series, Bulletin No. 5), is.sued by this 

 Department. Though Sesamia is a regular pest of sugar-cane, the moth has a marked 

 preference for maize seedlings, on which it deposits its eggs. As many as three or 

 four egg-batches are inserted between the leaf-sheaths and the stem ; these are 

 composed of 15 to 75 eggs. The young larvae tunnel into the stem of the young 

 plant, which soon withers, and the caterpillars then migrate to older plants, in which 

 the rest of their development is passed, the caterpillar sometimes pupating in the 

 stem of the plant. 



To gain an idea of the intensity of these attacks, the following is worth noting. 

 In March 1915, 35 acres of maize were planted on an estate, but so many of the 

 plants were destroyed that the yield amounted to that usually obtained from 1 J acres. 

 On another occasion about 800 yards between lines of canes were planted with 

 maize ; the plants were examined every day, and showed the following infestation • — 



1st day of examination, 90 plants infested and uprooted. 



101 

 88 



2nd 



3rd 



4th 



5th 



6th 



7th 



8tli 



9th 



10th 



nth 



12th 



64 



164 



160 



111 



120 



404 



1,925 



1,200 



1,200 



Total 5,627 plants. 



