130 INSECTS AFFECTING THE ORANGE. 



bark, and causing an exudation of gum which, seems, at certain seasons 

 of the year, to become one of its principal sources of food-supply. 



In obtaining this the ant is led by its instinct to make incisions at the 

 base of the largest and most vigorous leaders at a time when, having 

 nearly or completely attained their full growth, the young shoots are in 

 process of hardening and ripening their wood, and the flow of elaborated 

 sap to these parts is greatest, giving in consequence the most copious 

 exudation of gum from a wound, 



The ants make their attacks in force, and either girdle and kill the 

 shoots or cut so deeply into their bases that they bend over or break 

 off by their own weight. Sometimes, but rarely, the ants attack 

 the old bark of the trunk and larger branches and gnaw holes in it, 

 eating away the cambium layer without waiting for gum to exude. 

 When the flow is very copious the ants bring sand and mix with the 

 gum. This enables them to tunnel into it, and while some individuals 

 are continuing the excavation in the bark beneath, others are penetrat- 

 ing the gum thus hardened and removing it piecemeal to their nests. 



Habits of the Ant. Solenopsis xyloni is a mahogany-brown ant of me- 

 dium size. It is very pugnacious and stings sharply. It lives in large 

 colonies, making its nest in the earth, and after rains throwing up irreg- 

 ular heaps of finely-granular earth. These heaps swarm with ants, 

 among which are seen occasional individuals (workers major) with 

 enormously enlarged heads. It is exceedingly fond of the nectar of 

 plants and the honey-dew secreted by insects, and is a constant attend- 

 ant upon Plant-lice and Lecanium Scales on the Orange. During the 

 greater part of the year it is attracted by them alone, and its visits to 

 the trees are harmless, but in October and November, when these in- 

 sects are scarce, the ant turns its attention to the gum of the tree itself. 

 During these months the summer growth is hardening and the bark is 

 full of elaborated sap, containing a large amount of saccharine matter. 

 It is probably in this condition only that the ants find it palatable and 

 accept it in lieu of their ordinary food. 



Destroying Colonies. When not too near the tree, bisulphide of carbon 

 may be used in breaking up colonies of this ant in the same manner 

 as recommended for those of Termites. Pyrethrum powder, to the ac- 

 tion of which they are very susceptible, stirred into the soil about and 

 within their nest kills great numbers of the ants and frequently causes 

 the survivors to abandon the premises. Naphthaline, in the form of a 

 crystalline powder, used in the same way is equally effective in break- 

 ing up colonies. After frosty nights in winter, when the sun shines 

 warm on the following morning, the ants come out of the ground and 

 gather in clusters under fallen leaves or other objects affording them 

 protection from the wind with exposure to the warmth of the sun. At 

 such times an excellent opportunity is afforded to destroy the entire 

 colony by raking over the ground about the nests, at the same time 

 spraying the disturbed ants with kerosene or dusting them with pyreth- 

 rum. 



