Vol. X. No. 249. 



THE AGRICULTURAL NEWS. 



355 



BOOK SHELF. 



^ MAXUAL OF PHILIPPINE SILK CULTURE. 



By Charles S. Banks. Issued hy iJie lUireav. of Science, 

 Manila. 



This -work commences by staling that the first attempt 

 on the part of the Bureau of Science, Manila, to import and 

 propagate mulberry silkworms in the Philippine Islands was 

 made six years ago, and that the intention of the manual 

 which is the subject of this review is to collect all data 

 accumulated up to the present, for the purpose of assisting 

 in the production of silk on a commercial scale. The 

 value of I he work is increased by the fact that many sources 

 of information have been consulted in order to make use of 

 the experience of other writers who have laboured under con- 

 ditions similar to those in the Phili|ipines. At the com- 

 mencement it is pointed out that cleanliness, a regard for 

 detail, and perseverr.nce are the main matters required in 

 rearing silkworms. An interesting seclion follows, dealing 

 with the history of attemi)tg to introduce silk production 

 into the Philippines. 



A detailed description is afforded of tlie .Japanese race 

 of the mulberry silkworm {Bomhi/.c tuori), as well as of the 

 Bengal-Ceylon race, the latter of which has afforded the best 

 results in the Philippines. In regard to the life-history of 

 the silkworm, the most important feature of this is its 

 conne.xion with the feeding of the worm at the different 



stages. When it leaves the egg, the 



arva measures ,-\;-inch 



in length: at first it remains quiescent for three to four 

 hours. When it begins to show activity, it should have its 

 first food, in the shape of the tenderest young green leaves 

 from the tips of the mulberry .shoots, the leaves being 

 placed over the young larvae so as to be within reach. 

 When the leaves wilt, they are replaced by others laid whole 

 upon them: the larvae will usually reach these without 

 any assistance. The first stage lasts three or four days; 

 after this, the first moult takes place, and when this is com- 

 pleted the young silkworms are transferred to regular feed- 

 ing trays. For the j'oungest silkworm.s, the bottom of these 

 is usually formed of a vegetable fibre made into a coarse 

 mesh; for half-grown and full-grown silkworms, wire netting 

 of I'inch and -^-inch mesh is usually employed. For feeding 

 the worms in the second stage young leaves cut crosswise 

 into strips about 4-inch wide are placed in the trays standing 

 over the silkworms; the latter quickly climb up through the 

 meshes and commence to feed. It is pointed out that mul- 

 berry silkworms should always be fed in this way, as it is 

 cleanly, all refuse is left behind, it entails no necessity for 

 handling the insect, and it enables the attendants to discover 

 quickly and remove any silkworms which appear to be weak 

 and cannot climb up through the meshes, and are there- 

 fore probably diseased. During the second stage, which 

 lasts for three or four days, the worms are fed regularly 

 every three hours, from six o'clock in the morning until nine 

 o'clock at night. At the period of tlie second moult the 

 length of the silkworm is about ^-inch. At this stage care 

 must be taken to prevent overcrowding, as this is a most 

 fruitful source of disease. At the time of every moult the 

 worms cease to feed, and food should not be supplied until 

 after moulting is completed. 



At the third stage, the larva measures 1 inch in length, 

 and the period is from three to four days; during this 

 time the worms may be fed on whole leaf. In four to 

 five days the third moult takes place, followed by the 

 fourth moult, which leads to the fifth and last stage. In the 

 fourth stage the worms may safely be fed with fully-matured 

 leaf, which has been carefully washed. Before pupating, the 

 silkworms measure about 2^ to 3j inches. To reach this 

 stage they require 30,000 times their weight of food, of 

 which two-thirds is consumed and the rest wasted. A table 

 is given which .shows that the larvae from 30 grams of eggs, 

 which usually number 35,000 to 40,000 require 1,900 to 

 2,300 B). of leaves. When the insect is about to spin, it 

 ceases to eat, and begins to move its head about as if search- 

 ing for sonjething; it is then provided with a spinning place. 



The portion of the work to which attention has just been 

 given in some detail is succeeded by a table giving particulars 

 of the life-history of silkworms raised by the Department. It 

 is succeeded by an account of the Eri or castor silkworm* 

 (Attacus ricini). In the larval stage, this insect is fed on 

 the leaves of the castor-oil plant (Ricinus comiminis), and its 

 life-cycle in the Philippines corresponds very clo.sely with that 

 of the silkworm which has just been described. For feeding 

 this worm, the leaves do not require to be cut up, and trays 

 of the kind used for tlie ordinary silkworm may be employed. 

 The worm is allowed to spin on finely shredded, dry banana 

 leaves, or on dried leaves of Intperata exultata or Saccharmu 

 indicum, arranged in a wide basket having a depth of 6 inches. 

 One of the advantages of the cocoon of this insect is that the 

 moth can leave it without injuring the silk; the latter cannot, 

 however, be reeled as in the case of the mulberry silk cocoon, 

 but must be spun by means of a special apparatus. 



The interest of the information given in the manual 

 would tend to cause the reviewer to treat all parts of it in 

 the detailed manner that has just been employed. Space 

 does not, however, permit of this, and it must suffice to give 

 short attention to the main matters that are considered further 

 in the book. A short section dealing with wild silkworms is 

 followed by a very useful summary of the chief matters con- 

 nected with the enemies and diseases of silkworms, and it is 

 stated that little fearneed be entertained of outbreaks of disease 

 in the Philippines, as long as all eggs are inspected at the ento- 

 mological laboratory of the Bureau of Science, and growers are 

 careful not to keep dirty, crowded, or ill-ventilated silk houses. 

 As a measure against the introduction of diseases from other 

 countries, an Act was passed, in 1907, to prohibit the importa- 

 tion into the Philippine Islands, except by the Bureau of 

 Science, of silkworms, their eggs, or cocoons, or of the moth. 

 Succeeding matters deal rao?t usefully with the silk house, 

 the mulberry tree {M<irus alha), the production and shipping 

 of eggs, and the elaboration of silk, and the manual con- 

 cludes with an appendi.x, an adequate index, and with 

 a series of very good plates, the value of which would, 

 however, have been enhanced, if they had been accompanied 

 by a short description of each, in addition to the ordinary 

 references that are made in the text. 



A sufficient use has been made of part of the informa- 

 tion given in the manual to demonstrate the interest and 

 usefulness of the subjects with which it deals. This has 

 been made plain, further, by the information given as to the 

 nature of its contents; and it remains to be said that, in 

 view of the efficient way in which it treats of its subject, 

 it should be available for consultation wherever an active 

 interest is being taken taken in the production of natural silk. 



*A good account of the Eri silkworm is alsii given in the 

 Agricultural Ja-nrnal of IiidUi, Vol. IV, p. 125. 



