46 Indian Museum Notes. [Vol. VI. 



The Indigo Thrips. 



In April I received some wingless young and winged adults of a 

 species of thrips which was reported to be eating away the epidermis 

 of the leaves of indigo at Dalsingsarai. In May I had an oppor- 

 tunity of observing the insect at work. The damage done is pe- 

 culiar and the presence of the insect can be detected by the whitish 

 appearance of the indigo leaves caused by the insect eating away 

 the epidermis of the leaf. 



The wingless young were present in very large numbers. The 

 greater proportion of the plants attacked were stunted and a fair 

 percentage of the leaves (about 50 per cent.) of infested plants were 

 attacked. There were on an average from 6 to 12 insects on each leaf- 

 let. The wingless young are semi-transparent, slightly reddish in 

 colour. The legs almost colourless. As the insects are so minute 

 it is impossible to examine them properly without a fairly powerful 

 hand lens. 



The adult insect is winged, blackish in colour, abdomen pointed, 

 length about /3-th of an inch. They are extremely active and take flight 

 on the slightest provocation, It is therefore no easy matter to 

 observe them unless extreme caution is observed on approaching a 

 plant. 



These insects have a habit of moving their bodies in an extremely 

 aggressive way which would cause most people to imagine that they 

 are able to sting. 



When at rest the wings are laid flat on the back. 



The best way to obtain specimens is to use a small camel hair 

 brush moistened with spirit. If used with care the insects can be 

 caught on the tip and transferred to a phial of weak spirit. 



Examined under a microscope the four narrow wings fringed with 

 long hairs can be observed. 



As regards the damage done, the insect though small does a deal 

 of injury owing to its immense numbers. 



I have been unable so far to discover any sort of parasite on this 

 minute insect. 



Later I hope to be able to publish a more detailed paper on these 

 pests. I have, however, deemed it advisable to write this short 

 note upon these observations made during my tour to call the atten- 

 tion of planters to these pests. 1 



1 For various reasons I was unable this year to rear the ladybird 

 Chilocorus nigritus Fabr. in Calcutta. There would have been difficulties, 

 however, in propagating this ladybird in Behar, owing" to the almost total absence 

 of the Indigo Aphid in the Indigo districts this year. 



