20 



JOUBNAL OF HOBTICULTURE AND COTTAGE GARDENER. 



[ January 2, 1868. 



describing bow I succeeded, and where I failed in my manipu- 

 Utiona. — J. B., Bracken Hill. 



[I may be permitted to remind my friend, that I stated at 

 ih* time that the mode of adding Ligurian queens, which I 

 described as being the best with which I am acquainted, was 

 adapted only to moveable comb hives. For hives with fixed 

 oombs, his mode of operating is probably as good as any that 

 can be devised. — A Devon.shire Bee-keeper.] 



SILKWORM-REARING IN ENGLAND.— No. 4. 



Japanese Sillacorim. — I must more especially notice these 

 worms, which have been introduced into Europe during the 

 last few years, and are becoming much cultivated on account 

 of their exemption from the " atrofia " so prevalent in other 

 breeds. These are small worms of four sleeps, or changes of 

 ekin, and produce yellow, white, green, or sulphur-coloured 

 sUk. There is what is called the annual kind, which produces 

 only one crop. This is the most esteemed. Then there are 

 the "Bivoltiui and " Trevoltini," sorts producing two and 

 three crops, but which are not much sought after in consequence 

 of their produce being uncertain in very hot weather, and the 

 difficulty of always having sufficient leaves to feed them ; for 

 it is injurious, nay, impossible, to gather the leaves twice 

 without spoiling the mulberry trees ; indeed, in England these 

 should never be wholly stripped. 



On leaving Piedmont in August, 1867, I brought to England 

 with me eggs of the Trevoltini which were hatching on my 

 arrival in London, they being the third succession of eggs. 

 On reaching home I fed and reared the worms quite successfully. 

 The cocoons were .spun in October, and fresh eggs deposited 

 by the moths in November. I think, if for rearing in Eugland, 

 that the second crop would be the most useful, as it would be 

 produced in the hottest of the weather here, the first crop being 

 limited to the mere production of eggs, and in this way the 

 mirlberry leaves would remain tm the trees to grow large before 

 being used. I am not recommending the use of these silk- 

 worms rather than the annual kinds, but there are circumstances 

 in which they might be useful, especially in this climate. The 

 eggs of the annual breeds are to be kept, by proper management, 

 so as not to hatch too early in the spring, or until the mulberry 

 leaves are well advanced in growth. 



I once laid a nearly full-grown silkworm on a yonng gentle- 

 man's hand, to look at. He started with fright on feeling its 

 coldness, and innocently said, " Oh, dear ! how cold you keep 

 yonr silkworms ! " He did not know that silkw o ms are cold- 

 blooded. Many persons do not know it. The heat of the 

 silkworm's yellowish blood is about equal to that of the air 

 in which it lives. The greater the temperature the quicker 

 the functions of the worms, and therefore the faster the food 

 ia consumed and the silk produced. Cold, on the other hand, 

 retards the functions, and consequently the final result. 



When silkworms are within a day or so of their sleep, their 

 appetite considerably diminishes, which may be readily 

 observed by their not consuming the leaves so much as at 

 other times. During their sleep they eat nothing. After the 

 sleep and change of skin, which occupy two days, more or less, 

 they again begin to eat, although sparingly at first, but in a 

 •ouple of days they will be in full appetite. At each meal one 

 may readily judge what quantity of leaves to distribute over 

 them by the more or less rapid consumption. 



Just before their sleep they spin over the leaves, or other 

 cbjects on the tables or stages on which they are, a fine web, 

 hardly perceptible to the naked eye, over which they firmly 

 station themselves, and thus their old skins are held while 

 they walk out, leaving them behind. Wherever worms station 

 themselves to undergo this operation, they must not be 

 touched or moved, but remain under what fresh leaves are 

 given to those not yet ready to sleep, for it rarely happens that 

 all will do so the same day. The insect, during the sleep, keeps 

 the head upwards, remaining fixed like a statue, and showing 

 no sign of life unless interfered with. Immediately after the 

 change of skin it is weak, and remains a short time while 

 gaining strength before again eating. At the moment the 

 change of skin is going on, there may be seen a certain humour 

 exuding from the insect's body, between the old and new skin, 

 which doubtless facilitates the shifting of the then useless and 

 burdensome skin. 



The four changes of skin to which the insect is subject occur 

 at intervals of from six to eight days. After each of the first 

 three changes it increases in size to about double, but after the 



fourth change it becomes several times larger, growing rapidly 

 during the period of ten days or so before spinning. 



When the worm has arrived at its full size it ceases to eat, 

 and voids all excrements, becomes crisp about the skin above 

 the head, and transparent in the body. It then goes about in 

 search of a suitable place to produce the cone of silk. Mate- 

 rials for the purpose must be suppUed. It is usual on the 

 Continent to form a kind of hedge for the worms to work in, 

 by tying together branches in broom fashion with open heads, 

 and placing them upright on the worms' stages. 



The silkworm's li/e is divisible into seven periods, or " seven 

 ages " — viz., the period from the time of hatching to the first 

 sleep, from that to the second sleep, from the second to the 

 third sleep, from the third to the fourth, from the fourth sleep 

 to the spinning, from beginning to spin to the conversion into 

 the chrysalis, and the change from the chrysalis to the moth 

 or perfect state. The time occupied by the worm in spinning 

 is variously estimated at from four to six days ; but the chry- 

 salis is generally perfectly formed on the eighth day, and the 

 moth may be expected out of the cocoon in about fourteen days 

 more. These transformations depend, however, on the influ- 

 ence of more or less heat. 



The degree of boat most suitable in a silkworm-rearing room 

 is 70° Fah. ; I mean when artificial heat is employed, as it 

 must be ; but when the natural temperature is more, say even 

 above 80', it will not be injurious to the worms, provided 

 plenty of air be admitted to the room. I fix 70°, little over or 

 under, as the most beneficial for the worms during their entire 

 life. Sudden variations of temperature are hurtful, and much 

 of the success of silkworm-rearing is to be ascribed to the 

 correct regulation of the temperature, to the supply of the 

 leaves, to proper ventilation, and to cleanliness. 



A colder temperature is not really hurtful, but only retards 

 the worms' development, unless when they are about spinnmg, 

 in which case cold hardens the silky matter contained in their 

 bodies, and they then cannot emit the silk. A suffocating 

 heat is in general much more injurious than cold to a certain 

 extent. A stagnant humid atmosphere is more prejudicial, 

 especially when accompanied by too much heat. Dry weather 

 is favourable to the worms, and for gathering the leaves, which 

 should not be used in a wet state. Smoke will suffocate the 

 worms, and bad rooms must be guarded against, as also mice, 

 pigeons, and chickens, which will eat them with relish if allowed. 

 Flies are also tormenting, and should be removed from the 

 room or caught by some means. Light exercises a beneficial 

 influence on the insect, and at night a proper illumination is 

 beneficial. 



Care must be taken to avoid in the silkworm room putridity, 

 which may arise from various causes, such as neglect of clean- 

 liness, by allowing the excrements and waste leaves to accumu- 

 late on the stages where the worms are. 



Various experiments have been made to test the degree of 

 cold silkworms' eggs and silkworms themselves will endure 

 without destruction. The eggs have been exposed to severe 

 frost in alpine districts without the least injury. The worms 

 have been laid on ice for several minutes, and have survived 

 the shock. They may be immersed in water, and even when 

 apparently dead will revive, if not left too long therein. To- 

 bacco smoke and snuff will kill them, and death occurs instantly 

 if their eighteen breathing holes be stopped. 



Having said thus much by way of introduction, I think it 

 time to come to the more practical part, by noticing such 

 instruments and other articles as are necessary in rearing silk- 

 worms. — Leonard Harman, jdn. 



OUR LETTER BOX. 



Poultry Judges (A Subi^criber . — It ia sufficiently difficiUt already to 

 find well-qualified judges without our rendering it still more difficult by 

 casting suspicions on their decisions. If, as you suggest, "one hundred 

 first-riite judges" could be named, from whom a choice might be made, 

 there would be no difBeulty. We agree with you that judges sbonld not 

 be residents near the show ; but we otherwise differ from you. 



Book (IT. H. H.).—" The Pigeon Book," by B. P. Brent. You can have 

 it free by post from our office if you lorward twenty postage stamps with 

 your address. 



Aqcarium Masino [An Inquirer).— Wc know of no work that we can 

 recommend. 



Island of Pero. — *' I notice that a constant advertiser in the Journal 

 speaks of White Peruvian Musk Ducks as "imported from the island of 

 Peru." It is some years since I went to school, and I have forgotten my 

 geography. Where is the place ?— T. C H." 



Dark Brahma Cock (Fairplay). — It may have been a prizeta^er last 

 year. You had better write to the advertiser for particulars. 



