43 6 



NA TURE 



{Sept. 4, 1884 



maggot gained this place by entering through the stigma from 

 outside. 



My investigations extend from April 1883 to June of this 

 year, and are briefly summed up as follows : — 



Udschimya sericaria appears generally in the middle of 

 April, and attains maturity in the beginning of May, at the time 

 when mulberry-trees expand their spring leaves. The female 

 Hies, Hying in bushes of mulberry-trees during the months of 

 May and June, deposit their eggs on the under surface of the 

 leaves in close contact with the mid-rib, or else with the fine 

 ramified veins. 



The eggs are nearly oval in shape, tapering at one end, and 

 rounded at the other. They are very small in size, measuring 

 o'iSmm. in length, and o'^mm. in breadth, and generally 

 convex on the upper and flat on the under surface. The upper 

 convex surface, which is coloured blackish-brown, has a lustre, 

 and is marked out into hexagonal areas ; while the lower flat sur- 

 face, which is coloured grayish-brown, lacks lustre, and is only 

 faintly marked out into hexagonal areas. The whole egg is en- 

 veloped with a sticky substance, which fixe* it firmly with its 

 flat side on the under surface of the leaves. 



When the leaves on which the eggs are thus deposited are 

 given to the silkworms, they eat them whole along with the 

 leaves, without crushing them at all. At one to six hours after 

 the eggs are taken, they are hatched out near either end of the 

 digestive canal, and a tiny white maggot comes into existence. 

 After a while the maggot passes out of the alimentary canal 

 through the mucous membrane, with the aid of its horny hooked 

 tooth and of seta; provided on each segment, and enters directly 

 into one of the nervous ganglia found just under the digestive 

 canal. A thin transparent membrane which envelops the 

 ganglion becomes a protecting sac, inside which the maggot 

 lives, and takes nerve-cells as its food. As it grows in size, this 

 sac gradually enlarges, and finally rupturing, the maggot passes 

 out into the body-cavity. At this time it measures five to six 

 millimetres in length. 



The maggot now seeks the main stem of the trachea, which 

 forms a kind of chamber just inside the stigma of the silkworm, 

 and enters into it by making an opening with its hooked tooth. 

 It now sticks its head out into the body-cavity of the silkworm 

 through the opening by which it entered, and takes fat as its 

 food. Its posterior end, which is provided with two large 

 spiracles, is directed towards the stigma, and thus the maggot 

 the air which passes in through the latter. 



As the maggot grows, this newly-formed chamber in which it 

 rests also becomes larger, and the opening through which the 

 anterior end of the maggot is projected out into the body-cavity 

 of the silkworm becomes wider and wider, until the chamber 

 assumes the shape of a cup Around this cup a large amount 

 of fat is fixed by the maggot, probably with a watery fluid it 

 secretes of alkaline reaction, and thus the wall of the cup in- 

 creases in thickness and becomes very tough. The wall is 

 always coloured dark brown, owing pro'iably to the faeces of the 

 parasite and to the action of the secretion upon the fat in the 

 wall of the cup. In this position the maggot attains maturity ; 

 it then crawls out through an opening it makes at any portion 

 of the body of its host. If, however, the growth of the maggot 

 has been slow, it may be found in the trachea of the silkworm 

 after it has changed into a pupa. 



In either case, whether the larva; or the pupae have the para- 

 site in the trachea, the space around the stigma, inside which 

 the maggot is lodged, is always marked with a large dark brown 

 patch, so that the presence of the maggot is easily recognised by 

 looking at the stigma. 



If a larva or a pupa of the silkworm is once infested by 

 this parasite, its fate is sealed, and the cocoons made .by the 

 infested caterpillars are usually thin, and of much less value. 



Those maggots which become mature in the pupee of the 

 silkworm crawl out of the cocoon by making a round opening 

 at one pole, and such perforated cocoons are entirely useless 

 for reeling silk. 



The mature free mag'ot, coloured light yellow, is very active, 

 and searching for the comer of the case in which they are kept, 

 or crawling deep into the ground, changes soon into a black, 

 cylindrical pupa. There the pupa rest, through the winter, and 

 in the following spring a perfected fly hatches out by breaking 

 open the pupa-case. 



A dei riled aci ount with suggestions for the remedies will soon 

 be published in a Memoir of the University of Tokio. 



C. Sasaki 



University of Tokio. July- 



Singular Instance of Instinct 



Among the insects very common to Victoria is one popularly 

 known as the mason-fly. In form it is very like a gigantic 

 hornet ; the wings and legs are of an orange colour, as is 

 also the abdomen, which is decorated with broad black stripes. 

 It has a strange habit of building its nest, composed of tempered 

 mud, in keyholes. Mr. Ellery, F.R.S., the Government Astro- 

 nomer, tells me that this same fly often commences to build 

 within the tubes of their astronomical instruments. The nest is 

 rather peculiar. A layer of mud is first laid down, and a certain 

 number of eggs are laid. Then follows another layer of mud ; 

 on this are deposited a number of young spiders, paralysed but 

 not killed. Another layer of mud, more eggs, then mud, then 

 spiders again, and soon, until the nest is complete. The spiders 

 are evidently stored up as food for the grubs, as soon as hatched, 

 an arrangement already known to naturalists. This fly has a 

 very fierce aspect, and its nature evidently does not belie its 

 looks. It flies about with great liveliness, and when alighting, 

 its long black antenna; are kept in a state of constant motion. 

 Its favourite food seems to be spiders, which it is in the habit of 

 seeking for under the bark and in holes in the trunk of the 

 Eucalyptus. It order to catch them it burrows under the loose 

 bark, and in a few seconds generally issues forth again with 

 some larg :: or smaller prey between its mandibles. The enor- 

 mous bulk of some of the victims does not appear to intimidate 

 it in the least. Even the gigantic so-called tarantula (vulgarly 

 triantelope) is fearlessly attacked. I was one day walking 

 through a suburban park near Melbourne, and saw one of these 

 flies suddenly pounce down on the back of a large tarantula some 

 five inches in breadth, measuring from the ends of the legs. 

 The huge arachnidian succumbed at once. Resistance with an 

 adversary in such a position was altogether out of the question, 

 the only resource being to die, like Ciesar, becomingly. I watched 

 the fight, or rather the murder, for some minutes, and then 

 touching the assailant with the point of my umbrella, drove it away. 

 It only flew, however, to a short distance, and then returned, 

 flying so viciously round that I fully expected I should be 

 attacked. By flourishing the umbrella, however, I again drovi 

 it off, and it retired to a distance of about a hundred feet. I 

 then left the spider, but afterwards went back, and found the 

 mason-fly following up his victory as energetically as ever. I 

 drove it away again, left the spot, and again returned to find the 

 murderous work still going on. This was repeated some half a 

 dozen times, and at last, taking out a book, I sat down on a 

 seat resolving to see what would happen. The fly did not 

 reappear for nearly a quarter of an hour, and I thought it had 

 altogether departed. A small ditch ran beside the pathway, 

 anil, turning my eyes in that direction, I noticed the mason-fly 

 peeping through some blades of grass growing on the edge. It 

 was evidently waiting for me to leave the spot in order to secure 

 the full advantages of its victory. 



It may be mentioned that the tarantula is a great coward. 

 Some of our large spiders, if placed on an ants' nest, will "run 

 amuck" through the crowd, nipping with their immense man- 

 dibles scores of their assailants who may approach them. They 

 will do this several times in succession, and generally get away. 

 The tarantula, however, if placed in such a position, yields at 

 once, and, gathering up its long legs, expires with all dignity. I 

 have tried the experiment many times, when a run of six inches 

 would have secured the freedom of the tarantula, but even in 

 these 1 ases no effort was ever made to escape. One species of 

 spider, living under the bark of trees, the skin of the abdomen 

 of which is very soft, often proves a match for the ants, not by 

 fighting, but by stratagem. He plays his enemies a thoroughly 

 Parthian trick, throwing out a number of webs, which com- 

 pletely entangle them. This same spider, if thrown into a pool 

 of water, similarly throws out threads of web, and, these being 

 wafted to the shore, and adhering to an overhanging branch,, 

 enable'the spider to reach the land. Thomas Harrison 



244, Victoria Parade, East Melbourne, Victoria, July 9 



Przevalsky's Horse 

 It seems worth while to point out the close resemblance 

 between the figure of this horse in Nature for August 21 and 

 those found incised on antlers in the cave of La Madelaine, copied 

 in Hawkins' "Early Man." There is the same massive head, 

 the same hog-mane, absence of forelock, pointed ears, short 

 body, and powerful legs, while there seems even an indication 

 that the long hairs of the tail spring first from the middle of that. 



