82 



PLANT SANITATION. 



Entomological Notes. 



By E. Ernest Green, Uovernment Entomologist. 

 (Illustrated.) 



Amongst the various species of 'Nettle Grubs' that frequent the tea-bush 

 the larva of Thosea cervina seldom attracts much attention in Ceylon, though- - 

 under the name of the "Assam Nettle Grub" it is recognised as an important 

 tea-pest in parts of India (vide " Pests and Blight of the Tea Plant," 2nd Edition, 

 p. 203). I did not include this species in my account of the caterpillars affect- 

 ing the tea plant in Ceylon (Ft. B. G. Circular, Ser. I, No. 19) as it had not then 

 qualified for a place amongst serious tea pests ; and it was not until May of 

 the present year that I received notice of widespread damage by this caterpillar. 

 Specimens were then received from the Haputale district with the report that 

 they were present in millions and were attacking the best flushing tea on the 

 estate. 



This particular nettle grub is fully twice the size of either Thosea cervina 

 or Thosea, recta (the Morawak-korle nettle grub). It is of the usual form and is 

 amply provided with stinging hairs. It is of an apple green colour with an irregular 

 saddle-shaped patch on the middle of the back which varies considerably in 

 both size and colour. In some individuals the patch may be bright orange red ; 

 in others, of a brilliant violet tint ; or it may be variegated with red and white. 

 The younger individuals are usually the more brightly coloured. Specimens of 

 all age* were present at the same time. Some were full grown and commenced 

 to pupate on the Kith of May, others are still feeding. The moths commenced 

 to hatch out a fortnight after pupation. The cocoon is dark brown and smooth 

 and has been likened to a tea seed. Watt and Mann state that — in India— the 

 cocoon is constructed underground. In my breeding cases many of the cocoons 

 were attached to the leaves of the plant. To distinguish it from its allies the 

 species might be called the * saddle-backed nettle grub.' 



As with all serious caterpillar pests of the tea plant, the most effective 

 way to check the attack is to prune heavily and burn the prunings together 

 with all fallen leaves and rubbish from below the bushes. But where— owing 

 to the condition of the bushes— this treatment is considered too heroic, nothing 

 remains but to collect the caterpillars and cocoons by hand as thoroughly as 

 possible. 



I have another report of an attack of Morawak-korle 'Nettle Grub* 

 {Thosea recta) from the Kelati Valley. In this instance the caterpillars lirst 

 appeared upon the Albizzia trees and from thence spread on to the tea. 



I have received from the Haldummulla district a hitherto unrecorded tea- 

 peat.Itis one of the 'Mealy bugs' characterized by a fringe of very long waxy 

 processes which give the insect a star-like appearance. My correspondent reports 

 that "four or five tea bushes near the edge of the jungle are covered with 

 the insects." I have previously taken this species in lower Haputale and Koslanda 

 upon a species of wild Jasmine. It will be described in my Monograph of the 

 Ceylon Coccidae under the name of Phenacoccm ornatua. It is probable that 

 these tea bushes have been infected from a Jasmine plant in the neighbouring 

 jungle. 



