34 FARMERS' BULLETIN 843. 



ants, or termites. Pecan growers in certain sections are familiar 

 with, these pests under the name "wood lice," the insects being so 

 named because they often mine large galleries in dead wood and 

 foundation timbers. On account of their underground habits and 

 method of attack, termites usually escape detection until serious 

 damage has been done, and are destroyed with great difficulty. 

 The reports of injury to pecan trees have been confined for the most 

 part to seedlings 1 or 2 years old growing on recently cleared 

 land. Sometimes young budded and grafted pecan trees are in- 

 jured or killed by termite attacks, but in most if not all cases the 

 orchards were set out on new land containing an abundance of dead 

 wood and humus. 



As is the case with true ants, termites live in colonies, and because 

 of their similarity to ants in appearance and habits the name ^ white 

 ants" has come, into more or less common usage. Termites only 

 occasionally attack living trees, their principal and most serious 

 damage being done to foundation timbers and woodwork of build- 

 ings. In cut-over woodlands they often are prevalent under the 

 bark of dead logs or beneath the fragments of wood lying on the 

 ground. On small seedling trees from 1 to 2 years old the taproot 

 frequently is hollowed until little more than a shell of bark remains. 

 (Fig. 40.) Termites usually gain entrance to the trees below ground, 

 but their galleries may extend for an inch or so above the soil inside 

 the heartwood. Apparently they attack grafted trees at the point 

 where the graft has not^ healed over smoothly with the seedling 

 stock. 



The affected trees as a rule do not show any indication of injury 

 until they are damaged beyond remedy, and then they die very 

 quickly, as is shown by the sudden wilting of the leaves. 



CONTROL MEASURES. 



Because of the underground habits of termites it is difficult to 

 apply a direct remedy to affected trees. ' Since they live in colonies 

 and their nests usually are in the ground somewhere near the affected 

 trees, it is important not only to kill the termites within the trees, 

 but also to locate and destroy the inhabitants of the nests, in order 

 that permanent results may be obtained. Nests perhaps can be 

 destroyed best by pouring carbon disulphid into them and then 

 immediately packing the soil around the nest. This is a volatile 

 liquid, and the gas, being heavier than air, will penetrate all 

 recesses of the nest and cause the destruction of the termites. 

 Since carbon-disulphid treatment is somewhat dangerous to plant 

 life, care should be employed not to use very large dosages 

 around the trees. Sprinkling of tobacco dust in the nests and 

 around the roots of affected trees has been reported to give 

 good results, but the writer never has seen this treatment 



