504 INSECTS AJiROAD. 



begun on a small scale, and gradually enlarged in order to 

 accommodate the increasing population. There are many speci- 

 mens of Synceca nests in the British Museum, the largest of 

 which is rather more than two feet in length. 



The colour of the present species is blue, even the head having 

 a sliaht gloss of the same colour. The wings are brown. The 

 handsomest of all the species is perhaps Synceca cyanea, in which 

 the blue is exceedingly vivid. All the Syncecas are Brazilian 

 insects. 



The last of the Wasp tribe which will be described is that 

 which is represented in the accompanying illustration. It is 



l'i .. 273. — Pdlybia sericea. 

 (Reddish brown.) 



tailed Potybia sericea, both of which names are appropriate. The 

 generic name, Polybia, signifies "sociality," and the specific 

 term, sericea, or " silken," is applied to the insect in consequence 

 of the silken down which is spread profusely over the thorax. 

 Most of the Polybias are South American insects, though there 

 are some which come from the Celebes, and a few from New 

 Guinea and Borneo. 



The mode in which these insects make their nests is very 

 remarkable. Choosing a tolerably flat surface, mostly that of 

 a leaf, the little wasp begins by laying the foundation of a 

 number of hexagonal cells, sometimes as many as thirty or 

 forty in number. She then deposits an egg in each cell, and 

 proceeds to make some more. As the larvae are hatched and 



