PIONEERS OF COMMUNAL LIFE 



Parasol-wasps, insects which have adopted the unusual habit of 

 leading a nocturnal existence, a comb of this kind may be as 

 much as 1 8 inches in diameter, and it hangs from the forest trees 

 like a yellowish-grey parasol. At the bottom of each cell an egg is 

 laid ; from this a grub emerges, which hangs head downwards, and 

 is fed by the mother with masticated insects. When the larvae have 

 finished moulting they spin themselves cocoons, and each cell is 

 given a lid, under which the inmate pupates. The emerging wasps 

 help their mother, who may now be called a queen-wasp. It is true 

 that they too lay eggs in newly-constructed cells, but since they are 

 unfertiUzed only males emerge from them, for it is a law among 

 the Wasps and Bees that unfertilized eggs produce males, and 

 fertilized eggs females. When these males emerge they fertilize 

 some of the females, and these found nests of their own, in which 

 they become queens. In all the species of Field-wasp the State is 

 founded by a single female, and with her death is ceases to exist. 

 Even the European species of more highly evolved Wasps and 

 Hornets build nests that last only a year. In the spring a fertilized 

 female begins to build cells and lay eggs, until the first working 

 females come to her assistance; in the autumn the community 

 perishes, but a few fertilized females hibernate in dark corners, and 

 the following spring each builds a new nest elsewhere. In sunny 

 Brazil, a land of eternal summer, there is no need for this interrup- 

 tion of the communal life ; there the conditions are favourable to 

 the construction of large and durable nests, and so, according to 

 Ducke, the basin of the Amazon is richer in wasps than any other 

 region on earth. In the great wasps' nests of Brazil, such as those 

 built by the Parasol-wasp, we find, accordingly, several fertilized 

 females or queens, and the multiplication of communities is effected, 

 as in the case of our Hive-bees, by the departure of swarms which 

 construct a new nest, cell by cell, and enlarge it as their numbers 

 increase, or first prepare the whole nest, and only then proceed to 

 lay the eggs. 



The nests show all the stages of increasing perfection. The Palm- 

 wasps build comb over comb, connected by pillars of papier-mache, 

 in the roUed-up leaves of palms or bananas. Still other wasps shelter 

 their nests from the rain under large leaves, or even the roofs of 

 houses. The "Pasteboard-wasps" have another method. These 

 black insects, whose abdomens are adorned with yellow stripes, 

 give their combs such a durable cover that they are able to hang 

 their nest from the branch of a tall tree, where it looks Uke a huge, 



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