Life in La Plata 



229 



being at least four feet in diameter five feet from the 

 ground. Various species of acacia are grown, and seem to 

 propagate themselves as freely as does our locust-tree 

 (Robinia pseudacacia) . These plants seemed to be 

 particularly liable to the attack of a species of bag- 

 worm (GELketicus platensis) , innumerable cocoons of which 

 were pendent upon their branches. This same insect 

 appears to ravage the poplars and willows. The euca- 

 lyptus escapes from their at- 

 tacks, but I observed that a 

 great many species of decidu- 

 ous trees were infested by 

 these curious insects. The fe- 

 male is wingless, as is the case 

 with all of the species of the 

 genus; the male is able to fly. 

 The female remains in the co- 

 coon, and is little more than a 

 living mass of eggs. After fer- 

 tilization has occurred the eggs Fi - 23. Cocoon of (Eketi- 

 hatch, and, emerging from the cus platensis ' Nat ' size " 

 silken sack which has been the nuptial couch and then 

 the coffin of the mother, the little caterpillars crawl forth 

 and the cycle of life is renewed. The small water- 

 courses and shallow ponds which abound in the neigh- 

 borhood of La Plata are all beginning to be lined with 

 willows and osiers. In such places I also found Arundo 

 donax, the common reed of southern Europe. I saw a 

 couple of fields in the outskirts of La Plata where this 

 plant was being cultivated, but I observed that it had 

 also escaped in spots and was propagating itself. 

 According to Otto Kunze seventy-five per cent, of the 

 plants growing in the immediate vicinity of Buenos 

 Aires and La Plata are introduced species, the majority 



