EMEBGENCE OF TWO TUBE-DWELLING HOMOPTEEOUS INSECTS. 281 



into the froth which has accumulated on the lower side. There is constant move- 

 ment inside the mass of froth caused by the insect getting out of its nymphal skin. 

 The froth now gradually subsides ; all movement has ceased, and the newly- 

 emerged insect is seen clinging to the empty nymph skin, which in turn is clinging 

 to the side of the tube. 



The pale- yellow wingless insect remains quite motionless. After a short 

 interval tiny tegmina and wingbuds begin to appear. These expand rapidly, and 

 in half an hour from the time they were first seen are fully developed. While this 

 growth develops, and for some time after, the wings hang down perpendicularly ; 

 they are then suddenly flexed once or twice, and closed to their normal roof-like 

 position. At this stage, though rather soft, the insect is able to walk and jump, 

 but if left undisturbed it will remain quietly on the twig until the next day. 



The time occupied by the metamorphosis of this insect is about an hour, 

 and the total period from the first appearance of the froth, about two hours. The 

 capture of adult specimens by me, in September and January, proves that there are 

 two broods a year. 



POLYCHSTOPHYES SERPULIDIA Kiik. 

 This insect occurs in the Brisbane district, but more sparingly than the 

 previous species. The tubes differ from that species in their larger size, darker 

 colour, and the transverse serrated lines, which give them a coarser texture. They 

 are invariably attached to the twigs for their entire length, while in the previously 

 mentioned species, the upper part of the tube is always bent out away from the 

 twig. This causes a slight difference in the method of exit between the two species. 

 When the froth is coming from the tube it often runs down the twig instead of the 

 tube, dependent on the angle at which the twig is inclined. The emerging nymph 

 following the froth consequently often clings to the twig instead of the tube to 

 undergo its metamorphosis. When this occurs, the insect immediately after 

 emergence generally walks a little way up the twig and there stops while its wings 

 develop. In other respects its method of emergence is similar to that of 

 Pectinariophyes 2^€ctinaria, and the time occupied is about the same. 



F. Ratte remarks : — "' In the dry parts of the interior it is probable that the 

 water contained in these shells is resorted to for drinking by the ants so numerous 

 in Australia, as if it was a speciality among the small homopterous insects to provide 

 during their life for the Formicidae." All the evidence which I have acquired in 

 the coastal district is against the above opinion ; no ants have been seen drinking 

 the liquid, nor were any noticed in the vicinity of the tubes. It is well known that 

 many Coccidae, Membracidae, &c., excrete liquids which are eagerly sought by ants. 

 In return the Homoptera receive certain services from the ants, so the benefit is 

 reciprocal ; but in the case of these soft tube-dwelling nymphs it would be of no 

 service to be robbed of their protective liquid, without which they would speedily 

 perish. 



