Plant Sanitation* 



320 



[October, 1909. 



ochreous to bright red. The extremities 

 of the wings are black, and form, when 

 folded together, a conspicuous black 

 diamond-shaped patch. There are also 

 two black rounded spots situated just 

 in front of the terminal patch. A 

 narrow white transverse band forms a 

 collar immediately behind the head. 

 The under-surface of the body is con- 

 spicuously banded with white. 



Lefroy records that " the eggs are laid 

 in a loose mass under the surface of the 

 soil, usually in a crack or depression, 

 which the female covers with earth after 

 depositing the eggs. Each egg is round, 

 of a light yellow colour ; between 50 or 

 60 ate laid by each female. In less than 

 a week the eggs hatch to small active 

 red insects." 



The ' banded cotton- stainer' does not 

 confine its attentions to the cotton plant,, 

 but is found commonly upon Hibiscus 

 and numerous other plants. The insects 

 congregate on the cotton bolls, sucking 

 out the juice and even damaging the 

 contained seeds, especially after the 

 bursting of the pod. 



5. The 'Large Cotton-Stainers ' (Seri- 

 netha abdominalis and augur). I 

 have found both of these insects sucking 

 the seeds of burs-t cotton pods. They 

 differ from the last species in their 

 slightly larger size (from five-eighths to 

 three-quarters of an inch long), and in 

 the absence of the white collar and of 

 the two black spots on the wings. They 

 may be distinguished from each other by 

 their colour, abdominalis being ochreous 

 above and blackish beneath ; while augur 

 is red above and below. They each have 

 a large lozenge-shaped black patch at 

 the end of the folded wings. 



The remedy for all the different cotton- 

 stainers is to reduce their numbers by 

 every possible means. This may best be 

 effected by shaking the branches over a 

 sheet, when the insects fall off and may 

 be collected and thrown into vessels con- 

 taining kerosene and water. If this is 

 carried out systematically at the com- 

 mencement of the crop, much trouble 

 will be avoided later on. If — as is usually 

 the case— some of the bugs remain in the 

 lint after it has been picked, they will 

 quickly remove themselves when the 

 lint is spread out in the hot sun. 



Several Scale-bugs (Coccidoe) occur 

 with considerable frequency on cotton 

 stems, and must weaken the vitality of 

 the plants to a certain extent. The 

 three more common species are repre- 

 sentatives of the three larger families of 

 scale-insects, namely, the 'hard scales' 

 (Lecaniinoe), the ' mealy-bugs ' (Dactylo- 

 piince) and the ' armoured scales ' (Dias- 

 pidinoe). 



6. The 'Black Bug' (Lecanium nigrum) 

 is a small black limpet-like scale, 

 with a hard shiny shell beneath which 

 the countless eggs are deposited. The 

 newly-hatched insects— which are almost 

 invisible to the naked eye — swarm on to 

 the smaller twigs and branches, where 

 they attach themselves by their fine 

 hair-like proboscides for the rest of their 

 lives. They are at first very pale pinkish 

 yellow; but during growth, they gradu- 

 ally become darker, the pigment com- 

 mencing in the form of a network of 

 rpfldish brown lines ; finally becoming 

 biack or deep chestnut-brown. 



7. The 'Filamentous Mealy-Bug 'Dacty- 

 lopius virgatus) becomes conspicuous on 

 the younger stalks by the masses of 

 cottony or silky secretion with which it 

 surrounds itself. The adult insect is 

 soft and fleshy and of a pale yellowish 

 or pinkish colour which, however, is 

 almost completely obscured by a cover- 

 ing of white mealy powder. 



8. Hemichionaspis aspidistrce. It is 

 difficult to find a suitable popular name 

 for this insect. It might be called the 

 ' Scurfy Scale,' but that name has 

 already been adopted for a different 

 species that occurs in America. The 

 Americans term this species the ' Fern 

 Scale,' from the frequency with which it 

 occurs on cultivated ferns in that 

 country. In Ceylon, the insect appears 

 to be equally abundant upon fifty or 

 more different plants of widely different 

 orders, 



It affects the stems of the plant. The 

 females are very inconspicuous, being 

 covered by a thin scale of a very pale 

 reddish-brown colour which closely re- 

 sembles the tints of the bark. But the 

 males are concealed beneath a snowy- 

 white tricarinate scale, and — having the 

 habit of congregating together by them- 

 selves — form conspicuous white scurf- 

 like patches on the stems. 



It is questionable whether any effective 

 remedial measures against these scale- 

 insects would repay the cost. They can 

 be killed by spraying with kerosene 

 emulsion. But the effective life of the 

 plant is comparatively so short that the 

 bugs have not sufficient time to increase 

 to a really dangerous extent before the 

 old plants are uprooted and burnt to- 

 gether with all the insects upon them. 



Of the remaining insects associated 

 with the cotton plant in Ceylon, it will 

 be suffi2ient to speak very shortly. They 

 are not, at present, of sufficient im- 

 portance to necessitate special remedies. 



9. Helopeltis antonnii. I have, on one 

 occasion, observed a few specimens of 

 this insect on the cottou plant. But as 

 the field was in the immediate vicinity 



