October, 1909,] 



321 



Plant Sanitation. 



of a cacao plot, it is probable that they 

 had wandered from their usual habitat. 

 However, by confining them with young 

 shoots of cotton, I found that they would 

 feed readily upon this plant, causing the 

 characteristic brown spots that are al- 

 ways associated with the work of this 

 pest. 



The insect itself is almost too well 

 known to require description. It is one 

 of the leaf -sucking bugs, a slender insect, 

 with long antennae and legs, and popu- 

 larly supposed to resemble a mosquito. 

 It may be recognized by the presence of 

 a knobbed spine (somewhat like a drum- 

 stick) standing up erect from between 

 the bases of the wings. 



10. Callicratides rama- A pale green 

 bug, with hyaline wings, allied to and 

 having the same habits as the Helopeltis. 

 A few examples were found upon cotton 

 bushes on the Experiment Station, Pera- 

 deniya. 



11. Zeuzera coffeai. The 'Red Borer.' 

 This boring caterpillar is gradually 

 proving itself to be more or less omni- 

 vorous. I have a single record of a cot- 

 ton stem tunnelled by the red-borer. 



12. Syleptamultilinealis. The 'Cotton 

 Leaf-Roller.' The small greenish cater- 

 pillars of this moth are often present in 

 some numbers on thj cotton plant ; roll- 

 ing up the leaves and feeding upon their 

 infolded edges. The resulting moth 

 is a pretty insect, with pale creamy 

 wings upon which is an intricate net 

 work of delicate brown lines. The ex- 

 panded Wings measure a little over one 

 inch. 



13. Eupterote geminata. The hairy 

 caterpillars of this moth sometimes oc- 

 cur in bunches on the branches. They 

 feed at night and rest motionless during 

 the day. They should be handled with 

 caution as their hairs are capable of 

 causing painful irritation to a delicate 

 skin. The moth is of an ochreous yellow 

 colour, with an inconspicuous brownish 

 line extending across each wing, aud 

 two or three brownish spots between 

 that line and the outer margin. The 

 body of the moth is very furry. The 

 male measures nearly two inches across 

 the wings ; the female, two and a half 

 inches. 



14. Gracilaria species. A tiny cater- 

 pillar that feeds beneath the cuticle 

 of the green stems. Specimens of this 

 insect were received from the Kurune- 

 galla district; but they died before 

 completing their transformations. 



15. Puiloptera festuosa. A beautiful 

 bronzy metallic-green beetle, one inch 

 in length, belonging to the family Bup- 

 restidce. Collected on the cotton bushes 

 at the Experiment Station, Mahaillup- 

 palama. The larvaa of this family of 



41 



beetles are all borers; but as no damage 

 to the cotton was observed, it is probable 

 that the beetles had their proper home 

 in the surrounding jungle. 



16. Geocoris tricolor, A tiny stout- 

 bodied bug, with broad head and promi- 

 nent eyes. A number of these insects 

 were captured on the cotton plot at 

 Peradeniya. Bugs of this genus are 

 believed to be predatory upon other in- 

 sects. In this case they may have been 

 doing good work amongst the swarms of 

 the Dusky Cotton-Stainer. 



17. Flower Beetles. Numerous minute 

 beetles, of several species, wiil usually 

 be found frequenting the blossoms of 

 the cotton, They congregate amongst 

 the stamens and may possibly assist in 

 the fertilisation of the flowers by carry- 

 ing the pollen from one blossom to 

 another. 



In conclusion, I should like to empha- 

 sise the importance of treating the 

 cotton plant strictly as an annual. The 

 best way to check all the insect pests 

 that attack it, is to uproot and burn 

 the plants immediatly after the principal 

 crop. During the intervals, not a single 

 cotton plant should be permitted to re- 

 main in the ground. If this system is 

 conscientiously carried out, most of the 

 insects that are dependent upon the 

 cotton plant for their livelihood will be 

 destroyed or starved out before the 

 appearance of the next crop. A second 

 or even third crop might perhaps be 

 gathered from the same plants by 

 leaving them in the ground; but these 

 later crops will be much more severely 

 punished by pests of all kinds, and will 

 be a source of danger to fresh crops that 

 may overlap the old. For the same 

 reason, perennial (or tree) cottons should 

 not be cultivated anywhere in the vici- 

 nity of the annual varieties. 



As some of the cotton-stainers (and 

 probably some other cotton pests) fre- 

 quent the ' Silk-Cotton ' trees (Erio- 

 dendron and Bombax) when they are in 

 fruit, these trees also should be pro- 

 hibited on a cotton plantation. 



Recent experiments in the United 

 States have proved that it is not only 

 important to destroy the old bushes, 

 but that they should be destroyed 

 immediately after the collection of the 

 crop, to allow of the longest possible 

 interval between two successive crops. 

 A delay of three weeks increased the 

 percentage of boll-weevils that survived 

 the interval, from 3 to 15 ; seven weeks' 

 delay increased the number of survivors 

 to nearly 22 per cent.; ten weeks' delay 

 brought the figure up to 28 per cent. ; and 

 the retention of the old plants for three 

 months resulted in a percentage of 43£ 

 survivora. 



