:-J(J TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



better with the catkins. In other galls this pilosity 

 becomes enormously cleA^eloped and covers the gall 

 or galls with a thick matted clothing, which, when 

 young, is frequently more or less glutinous and 

 must thus serve as a protection. Other galls not 

 provided with hairs are covered with a gummy 

 secretion ^vhich, one would think, would be apt to 

 entangle insects. In the case of Ajjliilothrix 

 Sieboldi, as Dr. Adler relates,* this glutinous matter 

 indirectly protects the gall-flies in another way ; 

 for it is much relished by ants, which cover them 

 with earth and sand so as not to be entangled 

 themselves when getting the liquid. I have myself 

 noticed the ants on the galls of this species, and a 

 similar case has been discovered in America. 



The gall-flies again — and especially the larger 

 ones — are apt to be preyed upon by birds which dig 

 out the larvae from the galls. The large size of 

 many galls — e.g., Cynips Jmngarica — must here be of 

 use ; but the larvae, as well as the flies, have a 

 better protection from birds in their bodies giving 

 out a nasty smell, and we may therefore presume 

 that they do not taste very nicely. Cynips Kollari 

 is a case in i^oint. I have noticed in several 

 localities that, when it first appeared in them, it 

 was more or less preyed upon by the tom-tits, but 

 after the first season they are scarcely touched. 

 Dryophanta foil has quite a nasty smell. When 

 these large galls get a month or two old the 

 portion next the outer skin and the central chamber 

 becomes more or less friable ; it must also be of 

 rather an astringent nature, and scarcely agreeable 

 to the bird which gets (as it must do) some of it in 

 its mouth when piercing the gall to reach the 

 larva. Of this nature are the celebrated "Dead Sea 

 apples" of the East— " which tempt the eye, but 

 turn to ashes on the lip." 



Thus we discover precisely similar phenomena 

 among galls to what exists with external-feeding 

 * Zeits. f. n-issensch. Zoologie, xxxv. p. 172. 



