132 F. C. WILLCOCKS— A MEALY BUG 



Explanation of Table. 



Column I. — These figures are of relative value only, since in most of tlie streets there are 

 many young trees (about 5 5^ears of age or under), as well as blank spaces ; the trees which 

 formerly occupied these positions having died from some cause or anotlier. Young trees 

 and blanks have been included in the estimate of the full complement of lebbek trees wliich 

 should be present in each of the streets tabulated. The figures for each street must be taken 

 as only approximately correct. 



Column II. — Shows the number of trees in each street which were so severely attacked 

 ^y the mealy bug during the summer of 1909 that they were cut back in the manner shown 

 in fig. 9. • 



Column III. — Gives the number of '^ cut-back " trees which died subsequently and were 

 removed between August 1909 and February 1910, The death of these trees may be con- 

 sidered as having been directly caused by the mealy bug. 



The Tanzim Department, Ministry of Public Works, kindly supplied these figures. 



It will be observed that 50 per cent, of the trees that were cut back eventually succumbed. 



We are not in a position to attempt an estimate o£ the pecuniary loss wliich 

 has accrued from the depredations o£ the mealy bug during the past year, as 

 we have no data concerning the value of the trees killed by the pest. There 

 can be no doubt, however, that the loss will prove to be a heavy one. 'J'he 

 value of the trees already dead alone represents a sum of many thousands o£ 

 pounds sterling, since we believe that as high a value as £25 is placed on the 

 older trees. Presumably this sum is the capital value, and includes original 

 cost, cost of planting and subsequent care and maintenance. The trees which 

 were cut back, but are still living, have depreciated in value very considerably, 

 and it is not unlikely that a number may die in the near future. Moreover, 

 it' replanting is decided on — as it probably will be, in the case of the principnl 

 streets — these cri})pled trees will be removed and must be reckoned as a loss. 

 The cost of removing dead trees and the cost of replanting must be debited 

 to the account of the mealy bug. On the credit side may be placed the value 

 of the destroyed trees as timber. 



Natural Enemies. 



At present we have but a scanty knowledge of the parasitic and predaceous 

 enemies of fJ. perniciosus. 



Small parasitic Hymenoptera belonging to the family CiiALCiDiDiE appear 

 to play a very important role in the natural control of this pest. Three 

 members of this family have been reared from the mealy bug. Two of these 

 are quite common. One is a handsome little insect, with pale greyish green 

 eyes ; the vertex and frons of the head and the thorax bright orange to 

 orange-red in colour. The abdomen is dark and covered, especially laterally, 

 with lustrous silvery hairs. Legs dusky, shaded with grey. The antennae 



