o^ 



ANTS. 



imitation of an ant's c;m -ing antennae, according to Mordwilko, some 

 ^pccios of Traiim. Stoinachis, Pemphigus. I'cntaphis and Aphis extrude 

 the drops very gradually, indicating that the habit has become fixed 

 through association with ants. 



3. Many species of Aphididae that live habitually with ants have 

 developed a perianal circlet of stiff hairs which support the drop of 

 honey-dew till it can be imbibed by the ants. This circlet is lacking 

 in aphids that are rarely or never visited by ants (Mordwilko). 



4. Certain observations go to show that aphids, when visited by 

 ants, extract more of the plant juices than when unattended. Accord- 

 ing to Bos (1888) this is the case with Aphis paparcris when feeding 

 on bean plants. These are more seriously injured when Lasiits niger 

 is soliciting food from the aphids. 



5. Although the siphons are lacking in some aphids which are not 

 visited by ants, and either live solitary lives or are concealed in galls, 

 the absence or reduction of these repugnatorial glands is usually most 



--b 



FIG. 211. Caterpillars of Lyca-Jia pseudargiolns. (Edwards.) a. Posterior seg- 

 ments seen from above; .r, opening of honey gland; b, extensile organ; b', same fully 

 exserted ; c, one of the plumose hairs with which its tip is furnished ; d. organ with 

 hairs withdrawn, 



marked in species that live with ants, which presumably protect them 

 from many of their enemies. On the other hand, the siphons reach 

 their greatest development in some of the solitary and rather agile spe- 

 cies that are not attended by ants (Siphonoplwra and Rhdpahsiphniu ). 

 The adaptations on the part of the ants are, with a single doubtful 

 exception, all modifications in behavior and not in structure. 



1. Ants do not seize and kill aphids as they do when they encounter 

 other sedentary and defenceless insects. This was noticed by Linne 

 in the case of Formica ritfa, of which he says: " Adscendit arborem, ut 

 aphides illius vaccas mulgeat nee occidit." 



2. The ants stroke the aphids in a particular manner in order to 



