42G BIOLOGIC KELATTONS BETWEEN PLANTS AND ANTS. 



The ants protect their charges against the attacks of their enemies; 

 for example, against ichneumon flies that wish to deposit eggs in their 

 bodies, and this with an almost maternal vigilance. They also protect 

 them against wasps, greedy for the sugary secretion. If the ants have 

 installed themselves upon a plant near the aphides it is very difficult 

 for the wasps to drive them away. Those insects try to make the ants 

 fall, and succeed in doing so, but soon other ants come to replace the 

 fallen and the wasps are at length forced to give up the struggle. 



The solicitude of the ants for the aphides is sometimes carried so far 

 that they take them with them when they break up their nests. Such 

 is the case with Lasius fuliyineus and brunneus in whose hills is found 

 an aphis (Lachnus lonyirostris) that frequents the bark of certain trees. 

 When they change their domiciles the ants detach from the bark the 

 rostrum of the aphis which, deprived of its protectors, would remain 

 exposed to the attacks of its enemies. 



In certain cases ants not only profit by colonies of aphides formed 

 independently of their aid, but they also assist in founding others. 

 The Schizoneura vemista is a winged aphis that lives at the base of the 

 stem of certain grasses (Setaria). The ants tear the wings of the 

 winged insects which they find on the ground, then dig a gallery so 

 that they can reach a rootlet. The aphides having reached the nour- 

 ishing plant, found there a colony that becomes, for the ants, a true 

 subterranean dairy. To it roads are made in the ground to give pas- 

 sage to winged aphides charged with the dissemination of their species. 

 In this case the aphis does not seem able, without the aid of the ant, 

 to find the means of penetrating to the base of the plant that is to 

 nourish it. The infesting of the plant depends directly upon the ants. 

 A considerable number of aerial organs are thus peopled with aphides 

 by the direct action of ants who transport the insects to noninfested 

 plants. We will not dwell further upon the relations between aphides 

 and ants, which interest us only because of the damage doue to plants 

 by the cooperation of those insects. The facts are, besides, detailed in 

 most general treatises on entomology. 



The relations of ants with the Coccidce (scale insects) are essentially 

 the same as those they have with the Aphides (plant lice). In our 

 climate, where plant lice abound, they are, together with the Coccidce, 

 the only insects, or nearly so, that furnish ants with a true animal 

 honey dew. But in South America, where aphides are much more rare, 

 they appear to be replaced almost entirely by the larva; of homopterous 

 Hemiptera (Gercopides, and especially Membra tides). The relations of 

 ants with these insects have been studied by Beske, Swainson, and 

 Lund. Besides the protection which the ants afford to the insects that 

 excrete the honey dew they perhaps aid them in their moltings by 

 relieving them of their old skin. Delpino has described the relations 

 that occur in Italy between Camponotus pubescens and other ants and 

 the larva; of two Cicadellas (Tettiyometra virescens and Centrotus 



