Page:The Zoologist, 3rd series, vol 1 (1877).djvu/482

456 Mr. J. Jenner Weir mentioned a case of parthenogenesis in Lasiocampa quercus, which bad recently come under his notice.

The President read the following letter from Herr A.W.B. Grevelink, of the Hague, relating to the insects which attack the cocoa-nut trees in the West Indies:—

"At Barbadoes the cocoa-nut trees were all destroyed by the Aleyrodes cocoïs, which afterwards, according to Sir Robert Schomburgh, extended its ravages over Antigua, Nevis, St. Christopher's, and other islands, from which I infer that it did the same in Martinique, as that island lies in the same line with the rest. The year or years, however, in which all this happened I have never been able to make out, and all that I can gather on this point, from the 'History of Barbadoes,' is that the said trees had been planted after the hurricane of 1831, and that they had attained to maturity when the insect first showed itself, which, as regards the new plantations, cannot well have been earlier than 1837.

"Now it so happened that in March of the same year, whilst serving as Lieutenant on board II. M. Brig 'Echo,' then stationed in the West Indies, I assisted in carrying over from St. Pierre, Martinique, to Curaçao a considerable number of the nopal-plant (Cactus coccinillifera), peopled, of course, by the cochineal insect; and as it was not many months afterwards that, in the last-named island, the cocoa-nut trees on some of the estates began to show symptoms of being affected as if by blight, which on examination was pronounced to be caused by an insect of the Coccidæ or Coccus genus, many persons there have ever since held the opinion that it was introduced at the same time with the cochineal from Martinique, which opinion was not a little strengthened when, in 1839, tidings from that island stated that all the cocoa-nut trees there had been destroyed by an insect (name not mentioned), but which, all things considered, I have not the least doubt was the same species which ruined the cocoa-nut trees at Barbadoes.

"After making a voyage to Europe, I arrived again at Curaçao in the beginning of September, 1838, where I took charge of the estate St, Joris, belonging to my family, on which were about two thousand cocoa-nut trees, the greater part of which were then already in a sickly condition, caused evidently by a microscopic insect which covered every part of the crown and extended also deep down into the heart of the tree, though outwardly the stem remained free from them. I applied every means that could tend to arrest their progress, in which I persevered during several months, but without any perceptible effect, for the fronds turned yellow and dropped to the ground as before. Trees which when I arrived were still healthy successively caught the infection, their leaves withered, and after they, as well as the fruit-stalks, had all dropped, down came also the centre of the crown, when nothing remained but the lifeless trunk, a useless encumbrance