121 



A MEALY BUG INJURIOUS TO THE LEBBEK TREES 



OF CAIRO. 



By E. C. WILLCOCKS, 



Entomologist to the Khedevial Agricultural Society. 



AVith Appendices by Egbert Newstead, M.Sc, etc., and Eeank Hughes. 



(Plate X.) 



General. 



In a sub-tropical city like Cairo it is most important that, so far as possible, 

 the main streets be protected from the direct rays of a powerful sun by 

 numerous and healthy shade-giving trees. For this purpose, the Lebbek 

 (Albizzia lebbek) has been very extensively employed in Cairo, where it 

 affords a welcome shade, as well as adding very considerably to the appear- 

 ance of the streets. Until the summer of 1909, these trees have, on the 

 whole, filled their parts quite satisfactorily. They had only one serious 

 insect enemy to contend against, in the form of a longicorn beetle — Xystro- 

 cera globosa, Oliv. Hitherto this " borer " has been considered by far the 

 most important pest of the lebbek, since its attacks, although comparatively 

 slow in their effects on the life of the tree, are yet sure, and when extended 

 over a period of years have caused no little mortality amongst the shade-trees 

 of this city. During the past year the importance of this beetle has been, 

 so far as Cairo is concerned, somewhat eclipsed by the depredations of a 

 comparatively new pest — a mealy bug. This insect proves to be new to 

 science, and is described for the first time in the appendix to this paper 

 under the name of Dactylopius perniciosas, sp. n. 



Under certain, but apparently somewhat special conditions, the seriousness 

 of this insect as a shade-tree (lebbek) pest cannot be over-estimated. It does 

 not merely cause temporary injury to the infested trees, but may actually 

 destroy the " crown," if not the entire tree, in the short space of a few 

 months. On the other hand, the lebbek beetle or '' borer '^ takes, generally 

 speaking, several years to kill a tree. 



The lebbek mealy bug was first discovered in 1906 on some cotton plants 

 growing in the garden attached to the laboratories of the Khedivial Agri- 

 cultural Society, on Ghezireh Island. The insects were present in small 

 numbers only, and did not show signs of increasing to any great extent. 

 It seemed improbable that cotton, a plant grown as an annual, was anything 

 more than a chance host-plant of this insect. Such proved to be the case. 

 In 1907 it was traced to some lebbek trees growing in the road outside the 



BULL. EKT. RES. VOL. I. PART IT. JULY I9IO. M 



