622 RUBBER 



species of Psocus which was found to be swarming on 

 some sheet rubber on its arrival in Colombo from the 

 Federated Malay States. The rubber had evidently been 

 packed before it was quite dry, wjth the result that the 

 surface was covered with mould, upon which the small 

 insects were feeding. They were not doing any actual 

 injury, but their presence in such large numbers would 

 probably affect the market value of the rubber. 



Hymenoptera. 



The ends of stumped plants are very frequently 

 tunnelled by various small bees and wasps, which 

 habitually choose such situations for the construction of 

 their nests. Various species of Ceratina fill these tunnels 

 with cells containing a mixture of pollen and honey. 

 But the wasps store their cells with paralysed insects 

 destined for the nourishment of their young. Trypoxylon 

 intrudens provides small spiders, and Stigmus niger 

 employs Aphides for the purpose. 



When a plant is stumped the cut end usually dies back 

 to the next node, from which the new shoots will be 

 produced. It is the dead pith in this dry portion that 

 attracts the insects. They will not burrow into living 

 sappy stems, nor will they enter by any but a cut or 

 broken surface. It is possible that the excavation in the 

 dead part may lead to an extension of the decay; but 

 this has not been proved. Any possible danger from this 

 cause may be obviated by stumping the plant immediately 

 above the node, leaving, say, half an inch to prevent 

 chance of injury to the axillary buds. There would then 

 be little or no dead wood to attract the insects. Where 

 this precaution has not been taken, the terminal dead 

 parts should be cut or broken off as soon as they are 

 thoroughly dry. 



The deserted tunnels of these wasps and bees are 

 sometimes tenanted by a species of Thrips, which has 

 consequently been regarded with suspicion. But this 

 particular species is quite harmless, and may indeed be 

 a friend rather than an enemy. It is an insinuating little 

 creature, and penetrates into the galleries of the " shot- 



