THE AUSTRALIAN MUSEUM MAGAZINE. 



207 



When we examine a hole from which 

 a cicada has emerged, there is no accu- 

 mulation of dirt around the entrance, 

 as is the case with those insects which 

 tunnel into the ground. A question 

 that is often asked is : What then 

 becomes of the earth that the pupa 

 dislodges as it tunnels u]iwards to the 

 light :' The secret has been shown to 

 lie in the insect's method of excavating. 

 The front pair of legs of the pupa are 

 seen on examination to be much larger 

 and more powerful than the middle and 

 hind ])airs, the femur being broad and 

 spade-like, the tibia pick-like, while the 

 hooks of the tarsus can be likened to a 

 rake. With these powerful implements 

 the pupa pounds its way U])wards from 

 its earthly dwelling-place. The earth is 

 first dislodged by means of the strong 

 claws of the tibiae, and the debris raked 

 in towards the body by means of the 

 claws of the tarsus. The dirt is then 

 seized by the tibia and the large flat 

 femur, the legs are thrust outwards, 

 and the dirt is rannned hard against 

 the earth wall. In this manner the 

 wall to the tunnel is at length con- 

 structed. 



The writer has sometimes observed 

 a turret of clay placed over the openings 

 of the tunnels from which the pupae 

 have emerged, and, though this habit 

 is not confined to our Yellow Monday, 

 the reason for it is unknown. It has 

 been suggested that they serve to 

 protect the burrow from flooding, but 

 there does not appear to be enough 

 evidence to support this conjecture. 

 Another theory, which is probably the 

 correct one, is that the pupa comes to 

 the surface before it is quite ready to 

 emerge. It therefore constructs a tur- 

 ret as a temporary retreat. 



Though the cicada, when it emerges 

 from the ground is usually termed a 

 pupa, the name is really misleading, as 

 it is not a true pupa, such as we find in 

 moths and butterflies, where the ]ni]^a\ 

 stage indicates a quiescent condition 

 during which the insect is incapable of 

 movement. The cicada '' pupa " is, on 

 the other hand, extremely active, as we 

 have seen, and the term pupa is, there- 

 fore, used only as a matter of conveni- 

 ence. The pupa is very similar to the 



The adult cicada emerging from the pupal 

 shell. 



[Photo. — A. Miisgrari'. 



larvae, except that wing pads are present 

 during the pupal stage. 



TRANSFORMATION. 



According to Mr. Froggatt, the pujja 

 emerges from its tunnel about eight 

 o'clock in the evening. It then climbs 

 a tree, fence, or some similar object and 

 fastens itself firmly to the bark by means 

 of its claws. This is very necessary, as 

 the claws will have to bear the whole 

 weight of the insect during its move- 

 ments while the subsequent process of 

 transformation takes place. The skin 

 then splits down the middle of the 

 pupa's body, from the head to the first 

 segment of the abdomen, and the back 

 of the adult cicada emerges. Then 

 follows the head, after which the insect 

 falls over backwards and draws out the 

 legs and the wings. At the same time 

 the linings of the thoracic air tubes 

 which take the form of long white 

 threads, are drawn out of the body of 

 the adult. These are plainly seen in the 

 photograph of the old shell of the 

 Yellow Monday. The adult cicada now 

 bends back again into a forward posi- 

 tion, and seizing hold of the front of 

 the pupal shell draws out the abdomen. 

 After this growth is very rapid, the 

 wings gradually lengthening and be- 

 coming hard and dry, so that, when 

 morning dawns, the insect is ready to 



