i82 ANTS, BEES AND WASPS 



deposits an egg and closes the cell, her last care being to destroy 

 the projecting tunnel and so hide the entrance to the nest. One 

 of the most remarkable facts relating to this little wasp is that 

 she does not kill, but merely paralyses, her victims ; this, of course, 

 prevents decomposition, and the larva on emerging from the 

 egg finds a supply of perfectly fresh food awaiting it. 



Each family of Solitary Wasps has its own idea as to the best 

 food to provide for its progeny, and preys on a particular kind 

 of insect ; some choose beetles, some flies, others caterpillars, 

 aphides, species of Orthoptera or bees, while some store spiders 

 in their nests instead of insects. In almost every case the victims 

 are not killed outright but only rendered helpless, although whether 

 this is really necessary for the larva's welfare has been much dis- 

 puted, some authorities holding that the little creature flourishes 

 just as well if by some mischance the victims have been killed ; 

 but the generally accepted theory is that fresh meat is necessary 

 for its perfect development. 



There are no workers among the Solitary Wasps, only males 

 and females occur, and in those families which are parasitic in the 

 nests of bumble bees the females are wingless. The Fossorial 

 Hymenoptera are themselves subject to the attacks of other 

 parasitic insects which lay their eggs in the cells excavated and 

 stored by the industrious wasps, the result being that the right- 

 ful owner of the cell is either starved through the supply of food 

 being devoured by the parasites, or is itself devoured by the 

 intruders. 



Saw-flies are common insects in the field, wood, and garden, 

 but they are so unobtrusive in their habits and appearance that 

 they are not very generally known. Nevertheless, they are an 

 important family of insects, and in the larval stage are exceedingly 

 destructive to fruit, vegetable and various other crops. The female 

 Saw-fly is armed with a remarkable ovipositor in the form of a 

 double saw. Each tooth of the saw is itself serrated, making the 

 saw a perfect instrument for cutting and rasping. The saw is 

 used for making incisions in the leaves and stems of plants, and 

 in these the female deposits her eggs. The Saw-fly larvae resemble 

 the caterpillars of the Lepidoptera, but may be readily distin- 

 guished by their greater number of legs, Saw-fly larvse having 

 from eighteen to twenty-two. They are exceedingly voracious, 



