298 p. A. BUXTON. 



it." A plate is given showing the process in operation. I have no experience 

 of this method but do not understand how any dip can penetrate the spaces between 

 the leaf bases. No one but those who have endeavoured to separate date leaves 

 from the trunk or even from a small offset can reahze how firmly the petiole is 

 attached to the plant, and what an ideal refuge there is among all the fibrous material 

 which surrounds the bases of the petioles. 



Parlatoria zizyphi, Lucas. 



Various early authors refer to this scale as a pest of the date palm, and an un- 

 signed editorial article in Insect Life (1891) definitely says that " specimens proved 

 on comparison to be identical with P. zizyphi Lucas." There appear to be no more 

 recent records of P. zizyphi from date palms, and the above record dates from 

 before the publication of the description of P. blanchardi, to which it possibly refers. 



Phoenicococcus marlatti, CkU. 



Phoenicococcus marlatti, T.D.A. CockereU, Proc. Acad. Nat. Sci. Philadelphia 

 (1899), 1900, p. 262 (from imported Algerian date palms). 



Sphaerococcus draperi, R. Newstead, Quart. Jl. Inst. Comm. Ees. in Tropics, 

 1906 (from Egypt). 



Prof. Newstead tells me in a letter that his S. draperi is certainly identical with 

 Cockerell's P marlatti. 



Distribution. — Egypt and Algeria, both the Tel or Mediterranean coastal plain 

 and also the Saharan Oases. As an imported species, California and Arizona. 



Biology. — ^I failed to find this species in Mesopotamia. Very little seems to be 

 known of its habits. CockereU (1899) says that the female is 1-1 J mm. long, 

 and wine-red in colour ; she secretes wax but makes no true scale ; the embryos 

 grow to a large size in the body of the female. Marlatt found it, according to the 

 same author, occurring packed in great numbers " in little cavities about 10 or 12 

 mm. long by 4 or 5 broad on the midribs of the leaves, communicating with the 

 air by a narrow longitudinal slit," on date palms imported into America from Algeria. 

 The slight swellings containing the insects are very inconspicuous, and very likely 

 to be overlooked even on a close examination. Later CockereU himseU found it 

 on the sides of the sheathing bases of the leaves ; in this case it was not beneath 

 the epidermis, and Forbes (1907) speaks of it as remaining close to the trunk among 

 the great overlapping leaf-bases. Wilsie speaks of it as completely covering the 

 stalk of the inflorescence near its base, where it is completely concealed by the leaf- 

 bases. Probably Marlatt's original description of the Phoenicococcus Uving in cavities 

 on the leaf-base was taken from specimens which had started growing on very 

 young leaves ; as the leaf grew the tissues might have swoUen round the colony 

 of the scale-insect in such a manner as very nearly to cover it. Trabut's most 

 interesting note describes a date palm disease known to the natives of the oases 

 of Zibans in the Sahara as " khamedj" : this is caused by a heavy infestation of 

 the stem of the inflorescence by P. marlatti. The disease becomes evident in the 

 late spring soon a ter fertilisation ; the whole inflorescence dries up and no fruit 

 develops. This calamity happens to 5 per cent, of the trees, nearly the whole of 



