462 TRANSACTIONS OF THE 



that it appeared for the first time at Nice in 1743, and that Bernard wrote 

 on the subject in 1783; that there were no other writers before that time. 



That all the Roman authors of the first half of the eighteenth century 

 were silent upon the subject. It was in 1783 that all the proprietors in 

 some localities trimmed down their trees to mere trunks, in order to clean 

 them and commence with new trees. 



It is certain that a malady so characteristic with such a disagreeable 

 aspect could not have escaped the observation of authors. 



Abbe Coutoure presented a memoir e to the Academy of Marseilles, about 

 the same time that Bernard wrote, in which he declared that the Coccus 

 oleoe was observed for the first time in 1781. Captain Cousin states that 

 in 1861 this malady made terrible havoc in Kabylie (a part of Algeria), 

 where the olive formed almost the only resource of the people. It was the 

 more alarming because they could find no successful remedy. In Cousin's 

 report, he makes the statement that the greater part of the Kabyles pre- 

 ferred to leave the trees without any effort to remove the insects or the 

 black fungus, and that an orchard attacked would not give fruit before ten 

 years; thus intimating that the disease would die out of itself in about 

 that time. I have found in no other writings any intimation or possibility 

 of the let-alone theory accomplishing the work. 



Regarding the Coccus and the black fungus, there are various opinions; 

 some contend that the black is caused by the humidity, and the want of 

 ventilation and sunlight in the tree. This theory is accompanied by the 

 statement that the black fungus is seen without any appearance of the 

 Coccus; and that the Coccus is to be seen without any appearance of black 

 fungus. Some that it is caused by the smoke from chimneys; others that 

 it is caused by the northern winds carrying the sea air through the trees; 

 others, still, that it emanated from the ground. But the principal and ac- 

 cepted theory is, that it is caused by the attack of the Coccus; the piercing 

 of the bark of the limbs and twigs, by these little insects, causing the 

 emanation of sap, or some substance from the tree, or from the insect, or 

 both, which falls on the upper side of the leaves, as also on the trunk and 

 branches, and produces the fungus. 



In my examinations and observations I have never seen the black fun- 

 gus unless preceded by the insect, and that where the tree was affected, the 

 black was always on a lower level than where the insect was working; prov- 

 ing conclusively that the black was only a consequence of the insect work ; 

 and sometimes when there are comparatively few insects on a tree, it may 

 be several months before there is any appearance of black. 



When the fungus completely covers a tree, it is quite possible to destroy 

 the insects, and the black will remain for a long time afterwards; in fact, 

 when the trunk and branches or limbs are completely coated, it is very 

 difficult to get it off; it becomes a paste and adheres as firmly as glue, and 

 cannot be removed without the application of strong soap or some other 

 substance equally powerful. It is my opinion, that with little care large 

 districts could be kept free from this scale insect; I do not believe they 

 would spread a distance of ten miles, unless carried on plants. Birds will 

 spread them readily a distance of two miles. 



In closing this part of the subject I lay down the following facts: 



First. — That severe frosts will kill the insects, but the number of degrees 

 and limit as to time through which the cold should be extended, and yet 

 not do serious injury to the tree, is'beyond my knowledge, for the reason 

 that I have had no opportunity to extend my investigations. 



Second. — That trees planted close to the sea will resist the attack better 



