I46 SOME SOUTH INDIAN INSECTS, ETC. [CHAP. XV. 



i the point of view of control-measures the above divisions, 

 though artificial, possess a real importance, because different 

 methods of control have to be practised in regard to each of these 

 ] tive bugs, which are sometimes quite large insects 



and which are rarely minute in size, arc as a rule too large and 

 active to render feasible the operation of spraying even with a 

 contact insecticide but on the other hand their size and habits 

 admil of the satisfactory use of mechanical measures such as catch- 

 ing them by hand or in hand-nets or bag-net-. 



The second class, of semi-active bugs, contains insects such as 

 Apliids. Psyllids and Aleurodids, which are minute in size, soft- 

 bodied, and gregarious in habit. They are therefore best dealt 

 with by means of contact sprays such as crude oil emulsion or 

 tobacco wash. 



The third class, comprising the fixed bugs, includes practically 

 only the Scale-insects, which are often found in large numbers 

 within a small area and this is so, not because they are gregarious 

 bj habit, but simply because their radius of spread is circum- 

 cribed . and which are often protected by a filamentous or shield- 

 like waxy covering which secures them from the wetting effects of 

 rain and hence of ordinary aqueous solutions oi spray-material, 

 On account ol this waxy covering, therefore., it is usually advisable 

 to apply a spray which contains rosin, this substance having a 

 peculiar wetting effect on the waxy covering of the Scale-insects. 



The insects themselves are described and figured further on in 

 this book and we can only mention here a few of the more important 

 of the Bug Pests of crops. Of the 

 active bugs, the most injurious is 

 probably Leptocorisa varicornis, a long 

 slender greenish bug which attacks 

 paddy, sucking out the milky juice of 

 the grains just as these are formed; 

 it is easilj caught bj means ol hand- 

 Rio bug /Leptocorisa nets and is also attracted to light al 



"""""" s ' ' Ml,hl - night whilst its numbers should be 



ill Ii tidar, 1913-H , , .,,.,. 



checked as tar .is possible in the first 



b) due attention to the clean condition of the bunds sur- 

 rounding paddy-fields, as this bug will breed on wild grasses and 

 invade the paddy when this is ripening. Dysdercus cingulatus, a 

 brick-red bug with a black spot on each forewing and peculiar 

 whitish edges to the segments on the underside of the body, is a 

 common and destructive pest of cotton, piercing the bolls with 



I. and sucking the contents'ol the young seed, staining 

 thelint and spoiling the seed either for oil-extraction or for sowing ; 



