688 PHILOSOPHICAL TRANSACTIONS. [aNNO 1790. 



present, as far as the latter can be determined from the act of 2 George iii. 

 referred to above, or by any of the instruments now in use. 



XIX, Observations on the Sugar Ants.* By John Castles^ Esq. p. 346. 



The sugar ants, so called from their ruinous effects on the sugar-cane, first 

 made their appearance in Grenada about the year 1770, on a sugar plantation at 

 Petit Havre, a bay 5 or 6 miles from the town of St. George, the capital, con- 

 veniently situated for smuggling from Martinique. It was therefore concluded, 

 they were brought from thence in some vessel employed in that trade; which is 

 very probable, as colonies of them in like manner were afterwards propagated in 

 diff*erent parts of the island by droghers, or vessels employed in carrying stores, 

 &c. from one part of the island to another. Thence they continued to extend 

 themselves on all sides, for several years; destroying in succession every sugar 

 plantation between St. George's and St. John's, a space of about 12 miles. At 

 the same time colonies of them began to be observed in different parts of the 

 island, particularly at Duquesne on the north, and Calavini on the south side 

 of it. 



All attempts of the planters to put a stop to the ravages of these insects having 

 been found ineffectual, it well became the legislature to offer great public rewards 

 for discovering a practicable method of destroying them, so as to permit the cul- 

 tivation of the sugar-cane as formerly. Accordingly, an act was passed, by which 

 such discoverer was entitled to 20,000 pounds, to be paid from the public trea- 

 sury of the island. Many were the candidates on this occasion, but very far 

 were any of them from having any just claim: yet considerable sums of money 

 were granted, in consideration of trouble and expenses in making experiments. 

 In Grenada there had always been several species of ants, differing in size, colour, 

 &c. which however were perfectly innocent with respect to the sugar-cane. The 

 ants in question, on the contrary, were not only highly injurious to it, but to 

 several sorts of trees, such as the lime, lemon, orange, &c. 



These ants are of the middle size, of a slender make, of a dark red colour, 

 and remarkable for the quickness of their motions ; but their greatest peculiarities 

 were, their taste when applied to the tongue, the immensity of their number, 

 and their choice of places for their nests. All the other species of ants in Gre- 

 nada have a bitter musky taste. These, on the contrary, are acid in the highest 

 degree, and, when a number of them were rubbed together between the palms 

 of the hands, they emitted a strong vitriolic sulphureous smell; so much so, that 

 when this experiment was made, a gentleman conceived that it might be owing 

 to this quality that these insects were so unfriendly to vegetation. This criterion 



* This species of ant is perhaps the Formica saccharitora of the Gmelinian edition of the Systema 

 Naturae. 



