28 pests of coffee 



The Eelationship of Ants to the Green Bug. 



The general facts of the relationship between ants and 

 sucking insects such as scale insects, plant lice, leaf hop- 

 pers, etc., are well known. All of these groups of insects 

 produce a sugary excretion known usually as honey dew 

 which the ants take up with avidity. Text-iig. 6 shows a 

 cock-tailed ant {Cremastog aster sp.) "milking " a green bug. 

 The benefit derived by the ants from this relationship is 

 obvious. It is, however, not always so apparent just what 

 benefit, if any, is derived by the insects which are visited. 





Text-Figure 6. 



An ant {Cre7nastogaster ap.) in the act of " milking " a green bug. 



In some cases, as, for instance, that of the corn root 

 aphis {Aphis maidi-radicis) in America, the insect is prac- 

 tically helpless without the assistance of a species of ant 

 {Lasms uiger-americanus). When the plants upon which 

 these aphids live are no longer available, the ants 

 carry them into their nests and keep them until the 

 plants appear again. In South India an example of quite 

 close relationship between scale insect and ant is that of 

 the so-called cock-tailed black ant Cremastog aster sp. and 

 the scale Lecanium formicarii. This latter is found 

 only in the nests of the ants and if the ants' nests are 

 broken into the scale insects are carried away just as 

 carefully as are the pupse, larvse and eggs of the ants 

 themselves. It is obvious that, in such cases, any mea- 

 sures towards the checking or destruction of the scale 

 insects or plant lice would be incomplete if they did not 

 . take into consideration this relationship. 



In other cases, the relationship is not nearly so close 

 and in these it is always a question whether the ants are 

 in any way particularly beneficial to the scale insects. 

 Such a case is presented by the green bug. The most 

 casual observation shows that this scale insect is visited 



