1889.] 



THE YOUNG NATURALIST. 



It must not be thought that wing hooks, though so eminently 

 characteristic of Hymenoptera, are peculiar to that important division 

 of the insect kingdom, for in our next order, the Homoptem, family 

 Aphidce, or plant lice, a similar arrangement exists for the connection 

 of the wing. In these insects, which are only too familiar to gardeners 

 and agriculturists generally, the organs of flight are carried in a very 

 different manner to those of the orders already considered, being gently 

 deflexed or sloping like the roof of a house, and meeting at a very 

 acute angle over the back. The stigma is still present, that is to say, 

 in cases where the individuals have wings at all, it being no uncommon 

 thing to find them entirely absent. 



As a general rule, the wing hooks are arranged in a bunch and are 

 usually seven in number. Fig. 8 shows a highly magnified representa- 

 tion of the same as found on the wings of Schizo- 

 neura corni, and it will be at once seen that they 

 do not spring from a nervure, but from the 

 membrane itself, at which point the two layers 

 Fig. 8. probably unite and become thickened, so as to 



afford sufficient support. The hooks very closely resemble the pot- 

 hooks and hangers that marked our early initiation into the art and 

 mysteries of script, the recurved ends permitting every degree of 

 freedom when the attachment is made by means of the lip provided 

 for their reception. Nothing is wanting in these simple but wonder- 

 fully effective structures : the mere act of opening the wings — passing 

 the anterior forward by a sliding motion over the posterior — completes 

 the unity of the two members. 



Many of the exotic species of Homoptem are remarkable for the 

 extraordinary form taken by them, the thorax being prolonged over 

 the abdomen, and furnished with strange branchiate excrescences. 



A characteristic of the wings of most insects is the hairs or spines 

 with which the membranes are so plentifully besprinkled. They are 

 found of all degrees of length, and a single wing oftentimes exhibits 

 them in every gradation. Their bases are fixed in depressions in both 

 upper and under surfaces, a perfect ball and socket joint being formed 

 in many instances. They likewise undergo many curious modifica- 

 tions, and are represented in the Aphidae by pyramidal elevations of 

 both superficies. In most Diptera, a single hair springs from the 

 centre of each of the hexagonal areolae, to which reference has 

 already been made. They may, with some degree of truth, be said to 

 have their representatives upon the wings of moths and butterflies, in 

 the more highly developed form of scales, but are now so altered in out- 



