156 



Marvels of Insect Life* 



it to make a long sloping flight to its mine shaft. It will spend more than an hour, 

 if necessary, in the task of hauling its load to a favourable position for flying off. 



Riley found that in some of the cells there are two cicadas entombed with the 

 digger's egg, and in other cells only one ; and he supposes that one cicada suffices 

 to nourish a digger-grub that is to develop into a male, and that two are required 

 for the development of a female. Upon one of these an elongate w^hite egg is laid, 

 and this hatches in two or three days. The grub is broad at the hinder end and 

 tapers to a point forw^ards. The slender head is thrust bctw^een the joints of the 

 cicada's body, w^hose substance is thus entirely absorbed. In little more than 

 a week only the skin is left, and by that time the wasp-grub is full grown. It now 

 spends a couple of days in constructing a cocoon of mingled silk and earth, in 

 which a number of pores are left, apparently to allow air for the grub until its 

 change into the chrysalis stage. The cocoon is spun in early autumn, but the 

 change of the grub to the chrysalis does not take place until spring, and then it 

 is soon followed by the emergence of the perfect digger-wasp. 



The digger-wasp has serviceable jaws,, and soon cuts through the cocoon which 

 imprisons it and makes its way through the shaft to the outer world. In summer 



it is abundant in North America, and is 

 generally avoided on account of a well- 

 deserved reputation for the severity of its 

 sting. 



The Bug Family. 



The term bug is used here nut in the 

 sense in wdiich Americans commonly use 

 it as including Insects in general, but in 

 the sense understood by the British 

 naturalist, to whom it indicates one order 

 of Insect life,i an order that includes many remarkable forms, many beautiful 

 forms, and many whose ravages among plants make a knowledge of the 

 order important and even necessary to all who have to do with cultivated 

 vegetation. But, although something like eighteen thousand species have 

 been named, and over a thousand of these occur in the British Isles, 

 it remains one of the least studied orders of Insect life ; and, although we have 

 labelled and classified this considerable number of species, of only a few have we 

 learned anything of their natural history. These few, it is perhai')s unnecessary 

 to state, are mainly those that come conspicuously into antagonism witli man the 

 cultivator ; yet even in this restricted view of the family, there is much still to be 

 learned and many debatable points in their economy to be cleared up. 



One characteristic of the entire family is that they do not undergo a complete 

 metamorphosis. There is little difference of form between the infant and the 

 adult, though the acquisition of wings, of course, makes considerable dilference 

 of appearance in many species. In this matter of changing only by the acquisition 

 of wings they agree with members of the grasshopper and cockroach lamily ; - but 

 there is this difference, that whilst the latter have cutting-jaws througlujut life, 



1 Order Khynchota. ^ Orthoptera. 



Photo byl 



The Digger's Victim. 



lE.[Stfp, F.L.S. 



Having stung and carried off the cicada to its underground cell, 

 a single egg is deposited upon it, as shown. Occasionally two 

 cicadas may be found in a cell with only one wasp-egg. 



