SOLITARY AND SOCIAL WASPS 



them behave in almost the same way as the ichneumon. 

 The Scoliid wasps, which are common in most of the warmer 

 parts of the world, attack the underground grubs of cock- 

 chaferlike beetles. The wasp has powerful spiny legs by 

 which she can work her way underground to find her prey. 

 Some species sting the grub and lay an egg on it without 

 making any nest, leaving the grub in its own burrow. Others 

 do make a small underground cell to which they drag the 

 grub before laying on it. Most of the solitary wasps, how- 

 ever, make a nest, usually a gallery ending in one or more 

 cells either in the soil or in rotten wood. A few of them can 

 build beautiful mud cells, as described for instance by Fabre 

 in Pelopaeus (Sceliphron) ; less commonly they build cells 

 of vegetable matter such as leaves or resin. 



The nest-making solitary wasps fall into three principal 

 groups which have a different pattern of behaviour. The least 

 advanced type are the spider-hunters which first catch and 

 paralyse a spider, then hide it and look for a nesting-site. 

 Usually, they make only one cell at each place, and when 

 they have stored the spider in it wander off and repeat the 

 process. This pattern is not very different from that of 

 Scolia, and only very few of the spider-hunters make mud- 

 nests or construct several cells in one place. This means that 

 the position of the single cell has only to be remembered for 

 a short time, at most for a day or so, after which it is visited 

 no more. 



The sand wasps always make a nest before catching their 

 prey; this may be any sort of insect or spider. The nest 

 consists of several cells which are typically sub-divisions or 

 branches, often slightly enlarged, of a long tunnel. When 

 several prey are stored in the cell, the egg is normally laid 

 on the last one brought in and the cell is then closed. Thus 

 the mother has no contact with her young, but she must 



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