478 



Marvels of Insect Life, 



realize the absurdity of its action and left off. If such a substituted cell was already 

 provisioned but not closed in, and the nest taken away was beginning" to be filled 

 with honey and pollen, the bee would continue to pour provisions into the full 

 nest and finish by laying an egg where there was one already. 



It should be explained how Fabre was able to effect these alterations of the 

 positions of nests. In the ordinary course they are attached to rocks, and to attempt 

 to separate them from their base would almost certainly ruin the whole structure, 

 and would at least make it difficult and perhaps impossible to re-attach them in 

 such a way as would not vitiate the experiment by creating suspicion or aversion. 

 One particular species of mason-bee with which Fabre experimented builds its nests 



on small boulders brought down by the 

 Rhone m flood and scattered along its 

 shores. Some of these were not too 

 large to be handled, and these Fabre 

 varied in position to suit his purpose. 

 Where it is possible to do so, the 

 mason-bee selects an angle of the rock, 

 as shown in our photographs on page 479. 

 It is obvious that such a position gives 

 greater security. The bee's object, no 

 doubt, is to secure the firmer hold that 

 the angle affords, and the consequent 

 economy of labour and material ; but 

 there is the further advantage that the 

 blob of cement is less obtrusive in such 

 a situation than if attached to a plane 

 surface from which it stands out, and 

 is therefore less likely to be noticed by 

 a possible enemy. We have elsewhere 

 commented upon the wonderful industry 

 displayed by the mud-daubers in accu- 

 mulating the relatively enormous quan- 

 tity of clav or mud recpiired for one 

 of their daubs, but it must be admitted 

 that the industr\- of the mason-bee is 

 greater. The mud-dauber selects moist 

 lard, stony mass. The mason-bee uses 



Ilggs of a l^SOCID. 



A cluster of eggs dc-positpd upon a holly-leaf. A remarkable tiling 

 about these and other psocid eggs is that they are covered with a 

 slight web, probably for their protection. They are shown magnified 

 twelve times. 



mat(ii;il which she know: 



a 



will dry into 



dry, gritty stuff that has to be moistened grain by grain with her own adhesive 

 saliva before she can carry a load to the scene of her building operations. 



Although the hard cement of the mason-bee suffices to protect the contained 

 grub or chrysalis against extremes of temperature, it does not ensure immunity 

 from the attacks of parasites, who eat u]) the provisions and starve the grub, or cwn 

 eat the grub itself. One of these parasitical intruders is the beetle trichodes, which 

 we have described in a previous article (see page 310). Both Aristotle and PHny 

 describe the honey-bee as taking the precaution, when having to fly home in a strong 



