SERICICULTURE.

Akaroa Mail and Banks Peninsula Advertiser, Volume VI, Issue 589, 7 March 1882, Page 2

SERICICULTURE.

(Continued.) I am now engaged in trying the amount of nitrogeneous products and phosphates in our mulberry leaves, but have not been able to complete the examination in time for this paper. I can, however, state that the moisture and solid matters boar the following proportions:— Solid. Water. No. 1. Cape 41*9 58 ! 1 percent. " 2. Black 29-1 70-9 •• " 3. Alba, viz :— A. Kaempferi... 32-6 67-4 " B.Tartarica ... 33-0 670 " C. Hispanica ... 36-28 63-72 " " 4. Japonica 32-56 67.74 •' " 5. Muliicaulis... 32-58 6742 " And that I find in my preliminary experiments a full average of phosphates and nitrogenous compounds in the shape of a arlairy albumenons juice that has characters approaching more to soluble animal albumen like raw white of egg than to legnmin, or that form found in leguminous seeds; as peas and beans, &c. The healthy fresh leaf is quite neutral, and well loaded with chloropliyl, or green coloring matter,without lohich the insect soon fails in health. It will be seen that the biack mulberry leaf is not a good leaf for feeding on account of its superabundant moisture ; the toughness of its texture is also very much against its use. The common white wild Cape is the best, and gives the greatest amount of nourishment, whilst under pollard cultivation the leaf is large and tender. These proportions of moisture will vary with the age of the leaf, the younger containing most moisture and being more tender than the older and mature leaf. Captain Thomas Ilutton, in the paper referred to, says the young leaves arU to the old and matured as veal is to beef ; but that is only his facetious way of expresaing his idea that too young food is hurtful and not sufficiently nutritious, and he is right to a certain extent; but Nature points out that a spring-arriving larva requires spring leaves, consequently young and tender, and if trees are cultivated so as to have j such, a greaf point is gained, I will just mention that a damp hand that is covered with perspiiation should never touch the leaves, as it sickens the worms if they eat ."uch leaves, or often they only crawl about on them to their waste. The leaves should only be handled by the stem, and should be cut off the twigs, where such is done at all, with a pair of siissors. and allowed to fall on the insects. They must not be bruised, or be damp, or be covered with honeydew, or djst; this last is a very great difficulty here to overcome. To keep the leaves, I put them into a corner of the room, and throw a damp (well wrung) cloth over them, or I keep them in abread

pan or some similar jar, young shoots and leaf buds in a wide-mouthed bottle, in all of which situations they will keep fortyeight hours very well ; but the jars anc bottles must be kept well aired and dry and free from mouldiness each time they are emptied. Water on the leaves is very fatal to the worms. Tobacco has a curious eiroet on them, a plate, in which tobacco has been, causing stupefaction and, apparently, paralysis, and they perish from starvation and torpificntion after two or throe days. Possibly all narcotics will act similarly. The smoke is also very injurious—so, in fact, is any smoke. Pnissic acid and the cyanides destroy them instantly. In oxygen they are very lively, but rapidly die in carbonic acid gas, carbonic oxide gas, hydrogen, and other gases that do not support anima; iifo. They rapidly die in chlorine and nitrous acid gases, even if diluted considerably ; but a little chlorine, such as is given off by chloride of lime in a plaie, does not annoy or hurt them, but, on the contrary, seems beneficial. S'.lphur, as flowers or milk of sulphur, and free from acidity, is not hurtfid in very small quantity as a dust on the leaf, but in large quantity is so. tSulplunou3 acid or mineral acid on the leaves soon destroys them, They retire from all grease or turpentine, and if lightly oiled on the sides die of suffocation. The alkaline carbonates and phosphates, as a dust on the leaves, purge them, so also dci the salts of ammonia ; but many years ago I fed worms on the hollyhock leaf, that had been paid over with white of an loaf sugar, gum, and nitrate of ammonia in very dilute solution of water, and allowed to dry on the leaf. I think the proportions were—White two eggs (fowls), 100 grains of nitrate of ammonia, 200 grains Jump sugar, 400 grains gum arabic; three pints water to two quarts, according tv heat ol day. The insects were many of them the Spanish fawn-colored variety and some of the common pointed yellow cocoon sorts. They all did well on it. especially the Spanish. 1 arrived at tins

by examining worms feeding, or attempting to do so, on various leaves, when finding the hollyhock just the right texuira* with a mucilaginous juice, but wanting in the nitrogenous compounds, I supplied them artificially, as mentioned, having the idea of stimulating the silk secreting glands more tkan any other. Some of the worms of'the Spanisu breed became giants of nearly four inches in length. I merely allude to this experiment to show that worms can be reared quite artificially, bnt not perhaps successfully commercially. They will, as is well known, eat the leaves of lettuces if quite green and not bitter, and I am tiold they will live on fig leaves, but could never s»eceed in getting worms that had tasted mulberry to do so. There is a faint smell in the rooms where large number of worms are kept, and it is of the utmost consequence that iheir exhalations should not accumulate. There should always be liree ventilation, top and bottom, but not a strong draught; the humidity should be such that a plate of salt and bunch of seaweed remaining soft, neither getting hard aad dry, nor moist and dripping. Lime in a moist but caustic state is of great use in absorbing ihe carbonic acid of their exhalations. A good way of applying it is to dip an old bag or two in cream of lime, and let them hang up in some convenient place, changing them daily, and keeping them moist with a watering pan having a very fine rose. The frames and supports,.if washed or spunged oyer with a saturated solution of green vitriol twice a week, keep quite free from mildew or any fungoid taint ; this ia a point of the utmost importance, as the dung of the insect, if allowed to accumulate, acquires mouldinessin twentyfour hours, is most prejudicial, and perhaps will lay the foundation of an epidemic attack. Therefore to keep rooms in which a large number of insects are reared and fed in a healthy condition, have an eye to extreme cleaninese and quick removal of all used-up leaves, and accumulations of droppings; attend to ventilation and temperature, which should range from; 75dg to 84dg Fahr. ; keep bags of limewash hangiag up ,• wash the supports with eolution of green vitfoil, and occasionally, if there arise any unpleasant smell, have & plate of chloride of lime in the place, but not constantly. As to the supports, when the insects get out of their babyhood, the best and most open and airy must be adopted, so as to stimulate the tree position; if on a small scale, bags or canvas on a bedstead do well, or the same stretched flat and tight in any convenient way, or even corn seeks on shelves or benches, the sacka being doubled lengthways form inte ©pen support through which the air can circulate. On a large scale there is nothing like wire netting stretched between framing, and just the width usually met with of about twenty to twenty-four inches. The larger the worm the coarser the mesh may be. There is no fear of the worm falling through; it does not like the contact with the metal, and sticks to the remains of leaves and twigs. In this way free ventilation is kept up, similar to what the insect would have on a tree, and the droppings can be collected by having slanting partitions underneath. A little tremor being given to the framing, the droppings will fall through, and can be taken away. When the moisture in the leaves and room is just right, and the worms are healthy ; their droppings are dry and black, and dry without loosing shape or much contracting. When, however, they are soft and moist, and adhere where dropped, and are green like chopped leaves, there is 100 much moistHre or not enough ventilation. The leaves, if young for the age of the worm, and the season wet like we had last spring, must be spread and dried until limpness is just coming on; the temperature of the room must be raised and ventilation well kept up. If chloride of lime is objectionaele to the attendants—some people dislike the smell very much—cloths dipped in strong solution of chloride of zinc or aluminum, or in Condy's fluid (the permanganate of potash solution), can be used.

At present we are exempt from diseases amongst the worms .similar to those they are now suffering from in Europe and Western Asia, but we must nevertheless guard against their introduction by excluding all European ova'and attending to the condition, ot' our trees, The diseases from w/iiich the insects suffer in Europe seem to be mostly of an epidemic character. -Some have k>een proved to be eminently contagious, and to be the result of certain fungoid growths. Such is the muscardine, whilst the most fatal disease that is now devastating the stock in Europe is contagious, infectious, and hereditary, and is caused by ,n minute animal organism that is found in all parts of the insect in all its ages, in their excrejient and excretions of a fluid form, and in the ova—ac-

cording to late invnstigatcrs being similar in character to the organisms producing Asiatic cholera in man. We must therefore be very careful not to import the infection, as we have experienced the effect of such importations in the cabbage and turnip blight, unknown here before 1854, but stopping our supply of these esculents for years afterwards, and still severely felt •* at dry seasons. The greatest difficulty we have here is to keep an equal temperature, :■ or at least an appropriate one, I have known a variation of from 20 deg, to 30 deg. Fiih. in twelve hours, which is very fatal. The worms full of 4fe moist succulent food cannot exhale the moisture fast enough, and they swell up and die, I believe from a positive fermentation of the masticated and comminuted leaf in them ; the cold first stopping digestion, decay of the leaf following, the worms thicken out at the thorax, and a dark-yellowish green fluid exudes from their mouths, and they often hurst— / blown up with gas—and very rapidly putrify, going black in about six and rotting to a complete semi-fluid mass, smelling fike rotten fish. This is un- « doubtedly a disease arising from cold and damp, as dry food and a warm day stops it. I have not noticed any other disease here of any kind whatever. I was obliged last season, in the middle of the third age, to try the effect of starvation, and I found that the insects would stand an amount of it quite beyond my expectation. I had i more worms than I could get food for, so I I fed my fowls with them for some days, 1 but they got sick of them, and then I had' ■* I no remedy $>ut to destroy them, and a 8 1 some had been without food for forty- 1 eight hours, I thought I would see how M long they couhl go. I kept some from ■ Saturday morning until Wednesday night ** ■ (rive days) without food of any sort, and fl then fed them up. None died, and nearly jfl all recovered their full size. I then kept some until two-thirds had died, and that H was not before the followi.oK Sunday

night, or nine clear days, and then I fed -vVbat remained up again, and they did nearly as well. The silk is nearly as good as any other, and the worms seemed only "to have blotted those banyan days out of their existence, or to have hybernated ;during that time, i then tried whenever sudden cold cameonhow a general starvation would operate, and I found it so far beneficial that they did not get the dropsy and burst, and that the only drawback ■was a lengthening of their feeding ages. The food must be absolutely stopped —not partially—or the insects go on progressing as puny things, but when quite starved they become torpid, and remain stationary in life progress. I rather like this experiment (although perhaps the worm did not), as it teaches us how to prevent the fatal bursting. I am afraid I have entered into a lot of dry detail, but on such a subject, where we have much to learn "with regard to our local treatment, all recorded observations are of value.

(To be continued.)