I II \l\ VII] 



SYMBIOSIS \M> PARAS 



67 



their sweet excretion. In countries with a cold Winter the ants 

 nave ev en 1" is taking care of the eggs of Aphids through- 



out the winter, placing the young newly-hatched Aphids out on 

 plants in Spring during fine weather but taking them back to their 

 in bad weather or on cold nights. 



Fig. J.5. — Section of Xylocopa showing Mites in abdominal cavity. 

 (After Berli 



We must not omit mention of the extraordinary case displayed 

 l>\ the common large blue Carpenter Bees (Xylocopa), although this 

 is perhaps rather to be described as an example of symbiosis than 

 as one of pure parasitism. These bees have at the base of the 

 abdomen a chamber in which live small mites of the genus Greenia. 

 The mites are apparently of no use or inconvenience to the bee. 

 although perhaps they may teed on other mites which are true 

 parasites. 



Examples of true symbiotic relationships exist between many 

 ants and Aphids, Scale-insects, Caterpillars, Fulgorids, etc., the 

 ants tending and protecting the other insects which in return yield 

 a sweet excretion which is eagerly licked up by the ants. These 

 relationships may prove of great practical importance in the control 

 of insect-pests, as the ants often deliberate] y carry scale-insects on 

 to plants previously uninfested, and may also prevent predators or 

 parasites from attacking their proteges. I have actually seen an ant 

 standing guard over a scale-insect and warding off the attack of a 

 parasitic fly which was trying to la\ its eggs in the scale. The 

 -pillars of some of the Lycaenid butterflies, as noted above, are 

 apparently absolutely dependent on the removal of their sweet 

 excretions by ants and cannot survive unless the ants are allowed 

 -s to them, and t -i i s. fact could doubtless be turned to practical 



The name Gieeuia, being preoccupied in Insecta, will have i" be changed. 



