1889.] 



THE YOUNG NATURALIST. 



95 



found in Bombus terrestris, twenty-three in number, and shaped like 

 inverted letter Vs. 



Fig. 3. 



An examination of the interior margin of the upper wing will show 

 that it is, immediately above the hooks on the under wing, turned 

 over to form a ridge or channel, the membrane of that particular part 

 being of a horny texture — extremely strong and tough. This ten- 

 dency of the membrane to adapt itself to requirements is exceedingly 

 interesting, but it does not so much alter its quality as its quantity, being 

 thickened to a more or less degree as the exigencies of the case 

 demand. This ridge, then, forms a most convenient receptacle for 

 the hooks, which fall naturally into it at such times when the wings 

 are extended for flight. 



Advantage of this tendency is taken when setting Hymenoptera 

 for the cabinet, the hooks drawing up the under wings into a natural 

 position with the anterior pair, and thus enabling both sets to be 

 expanded with facility. Too little attention is paid by collectors to 

 natural setting, more regard for personal " fads " being indulged in 

 than is in many cases justifiable. I have seen many beautiful insects 

 rendered utterly worthless as natural studies by a weakness of this 

 description. The wings set flat, curved, angular, brought forward to 

 a position that would destroy the function of every muscle, hung back 

 with a shamefaced slouch, parting company when they should be 

 attached, squeezed together in instances where they ought to be 

 divided, and in fine, some absurd notion indulged in to the exclusion 

 of all others. Hence, in setting Hymenoptera, it is necessary to see 

 that the wings are fairly hooked together before bracing down. 



It is evident, or will become so on reflection, that the wing hooks 

 are, in reality, merely modified bristles, as the transition from the 

 one to the other is very marked in some species. In the example 

 before us, the change from hook to bristle is abrupt, but in the case of 

 the gall fly from the oak, Spathegaster baccarum (Fig. 4), the transfor- 



