4o8 



NATURE 



[December io, 1914 



Sheep-maggot Flies. 

 Mr. W. W. Froggatt exhibited specimens of four 

 species of Diptera, the larvae of which have been 

 found on sheep in New South Wales. The common 

 blow- fly (Calliphora villosa) is a serious pest to wool- 

 growers, as it "blows" the soiled wool on the backs 

 of living sheep, and the resulting maggots feed upon 

 the wool-substances, and when full grown fall out 

 and pupate on the ground. This fly will also "blow" 

 meat or any kind of animal matter. Two other 

 species of Calliphora (oceaniae and rufifacies) also 

 attack sheep and all kinds of animal matter. The 

 fourth fly — Lticilia sericata, the green-bottle flv — is 

 the common sheep-maggot fly in Britain, but although 

 found at times breeding in living wool in Australia, 

 is not common in living wool, but is found about 

 Sydney commonly living on all kinds of animal and 

 vegetable matter, and congregating on plants and 

 shrubs. Although it will "blow" meat placed out- 

 side, it seldom enters houses as do the common blow- 

 flies. C. rufifacies had not been recognised as a 

 sheep-fly as late as 1910, and had not up to that date 

 been bred from the maggots found in soiled wool, 

 though in the west of New South Wales the fly was 

 plentiful about killiner yards, freshly skinned sheep, 

 and dead animals. This fly seems to have recentl}'^ 

 adopted the habit of "blowing" the wool owing to 

 the presence of soiled and "smelly" wool, and in the 

 north and west of the state this is now the common 

 sheep-maggot fly, while the two other species do com- 

 paratively little damage in those areas. Mr. Froggatt 

 also exhibited a Chalcid (Nasonia brevicornis) which 

 was found to infest the larvae and pupae of C. rufi- 

 facies, and remarked that the discovery of this para- 

 site was important and might possibly lead to new 

 methods of control of the sheiep-maggot flies. 



The Emergence of the Nymph of An ax papuensis. 

 Mr. R. J. Tillyard described the emergence of the 

 nymph of this insect (order Odonata). During the 

 three davs previous to hatching, the beats of the dorsal 

 vessel increase in number from about 30 to nearly 

 100 per minute, and just before hatching a cephalic 

 heart appears in the posterior head region which 

 ■drives blood forward into the head. The pressure 

 thus caused forces off the cap of the e^rg and the 

 nymph emerges quickly, swathed in an outer sheath 

 (the "amniotic covering," Balfour Browne), which 

 is found to be a non-cellular chitinous cuticle, not 

 related in any way to the amnion, but representing 

 the first moult of the larva. The swathed stage, 

 which may be termed the pro-nymph, lasts only a 

 few seconds. The cephalic heart increases enormously 

 and consists of two large chambers which pulsate 

 regularly and drive blood into the head. The latter 

 quickly swells to twice its original size, and thus the 

 pro-nymphal sheath is split dorsally and the young 

 nymph emerges, freeing itself from the sheath by a 

 few convulsive struggles. The cephalic heart quickly 

 subsides in the free nymph. Meanwhile a rectal 

 pulsating organ pumps water into the rectum, the 

 "branchial basket there being thus distended, and the 

 whole tracheal system of the nymph becomes gradually 

 filled with air. It is suggested that the rupture and 

 atrophy of the amnion, described by Brandt in the 

 embryology of Odonata, is due to the formation of 

 the pro-nymphal sheath, which forms a close-fitting 

 and far more efficient protection to the embryo. 



Scent-distributing Apparatus in Lepidoptera. 

 Dr. F. A. Dixey pointed out that certain specialised 

 scales found in various situations on the wings, bodies, 

 and limbs of Lepidoptera are well known to be con- 

 cerned in the distribution of a scent, which is in many 

 cases characteristic of the species. These scales may 



NO. 2354, VOL. 94] 



occur in both sexes, but certain forms of them, e.g. 

 the plume-scales of Pierines and Nymphalines, have 

 been found only in males. The Pierine plume-scale 

 often affords a ready means of identifying the species, 

 and is frequently of service in throwing light on 

 questions of affinity. 



In some cases a special adaptation exists with the 

 object of economising the scent until it is required for 

 purposes of sexual recognition or attraction ; for in- 

 stance, the costal folds of the fore wing in many 

 Hesperids, and the collection (seen in many Pierines 

 and in some Satyrines and Nymphalines) of the scent- 

 distributing scales into a patch, situated on that por- 

 tion of the fore or hind wing which is covered in the 

 position of rest. 



Mimicry. 



Prof. Poulton, after remarking that Australia is the 

 most isolated of all the inhabited continental tracts, 

 considered how far this is reflected in the insect- 

 models and their mimics, and stated that although the 

 subject had hitherto been little studied in Australian 

 material, there were already conclusions of much 

 interest. 



Perhaps the most widely spread models in the world 

 are the black, yellow-banded, stinging Hymenoptera. 

 The central members of these powerful combinations 

 are wasps (Diploptera), around which are ranged sand- 

 wasps (Fossores), and, in far smaller numbers, bees 

 (Anthophila), followed by mimetic species of the 

 phytophagous Hymenoptera, and of other orders — 

 Diptera, Coleoptera, Lepidoptera, etc. Throughout 

 this dominant combination of models and mimics the 

 sub-cylindrical body is black, encircled by many bright 

 yellow bands ; although widespread over the world, it 

 is especially powerful in the north temperate zone. In 

 Australia, however, its place is taken by a combination 

 with a distinct pattern; the bands are deep-brownish 

 oranp'e (instead of yellow), and are few and broad 

 (instead of many and narrow). This pattern runs 

 through a large and complex set of models and 

 mimics. Prof. Poulton remarked that it was very 

 convincing to compare such a mimetic Asilid fly as 

 the European Asihis crabroniformis with the Austra- 

 lian species, and to observe how their very different 

 patterns resemble those of the respective Aculeate 

 models, and that an equally significant comparison 

 may be drawn between the mimetic Longicorn beetles 

 of these two parts of the world. 



A question as to whether insects in different geo- 

 graphical areas . resembled each other in colour and 

 pattern was answered by Dr. Dixey, who stated that 

 such cases did occur, but were very exceptional, and 

 should, in his opinion, be regarded as mere coinci- 

 dences. There were no such coincidences known 

 where complex patterns were involved, but when a 

 simple pattern is concerned it may occur more com- 

 monly in widely different parts of the world. 



Experiments on Silkworms. 

 Prof. Otto Maas gave an account of his experiments 

 on the feeding of silkworms on different foods, e.g. 

 mulberrv and Scorzonera. When both parents were 

 fed on Scorzonera the capacity of fertilisation is much 

 Inferior to normal, the number of eggs deposited is 

 much fewer, and of the eggs fertilised fewer hatch. 

 In the case where only one parent is fed on Scorzonera 

 the mating may be as fertile as a normal one. A 

 cross between a Scorzonera-fed and a mulberry-fed 

 strain seemed to be superior In strength to one fed 

 only on mulberry. 



Species of Victorian Lampreys. 

 Dr. J. A. Leach stated that examination of 46 

 lampreys in the National Museum and the University 

 Museum, Melbourne, showed a remarkable amount of 



