502 SOME SOI Ml INDIAN INSECTS. ETC. 



insecticide. For root-living form, application of Crude Oil Emul- 

 sion or Kerosinc Emulsion or digging in Tobacco Refuse around 

 the roots. 



The following has lately been recommended in Europe but has 

 not yet been tested in India. A paint is prepared of Linseed Oil 

 7 lb.. White Lead L lb.. Zinc Oxide 1 lb., and this is boiled for 

 10 minutes and, when cold, i lb. of Turpentine is added. The 

 paint is applied by means of a brush to all the affected parts. 

 [Rome Bull. (1913), 491.] 



R \(.l ROOT APHIS. (See figure on page 501.) 



Distribution. — Only noted at Coimbatore in August and Septem- 

 ber, but will probably be found to be widely distributed in the 

 Plains. 



Lifehistory. -The whole lifehistory is passed underground on the 



roots of ragi plants. The young, which arc probably always pro- 

 duced .dive, are very minute, slender, pale-yellowish-white, of the 

 shape shown in the figure. They suck the juices from the roots of 

 the foodplant and. as the) grow, the abdomen increases in size 

 until it assumes a globular form of about the size of a pin's head. 

 A few winged viviparous females are also found on the roots but 

 no males have been observed, so that reproduction is apparently 

 normally agamogenetic. These Aphids are attended by several 

 ants, of which the commonest and most conspicuous is Camponotus 

 compressus, and the plants attacked may generally be picket! out by 

 the heap of small grains of earth around the stem, marking the 

 situations where the ants have excavated chambers into the soil to 

 visit the Aphids for the purpose of obtaining "honey-dew." The 

 ants also probably carry the Aphids into new localities but the 

 latter are also distributed by the winged adults. 



Foodplants. - Ragi. 



Status. — This insect may be a serious pest, sucking the juices ot 

 i he plants so persistently that the whole crop may wither unless 

 constantly irrigated and even then the yield is considerably 

 reduced. 



Control. — This is a very difficult insect to attack, as its under- 

 ground habit- make control measures difficult. The addition of 

 Crude Oil Emulsion to the irrigation wati r has be n tried with sonic 

 succe-s but this is not economic ally possible cm a large scale. 

 M" earching out and :l truction ol thi ants' nests around the 

 ragi ti' Ids may p< rhaps yi< Id betl 



Remarks. — In general appi recalls 



