D8 



THE AGRICULTURAL NEWS. 



Febeuaky 17, 190G, 



INSECT NOTES. 



Ground Pearls. 



JIany residents in the tropics are familiar with the 

 ground jiearls which are often to lie seen in the soil of garden 

 plots, and cultivated fields. To tourists they are ofl'ered 

 for sale either in bulk, or made up into necklaces. It is 

 probable that very few persons realize that these interesting 

 objects are made by in.sects, and are similar to the various 

 scales and blights that infest many of the wild and cultivated 

 l>lants in the West Indies. 



The ground pearl is the waxy shell of a small insect 

 which gradually builds up this protective covering from its 

 body secretions. The shape varies, but as a general rule it 

 is rounded. The size varies also. Many of them are small, 

 but some reach a size of 6 m.ni. (| inch) in length, and many 

 are 5 m.m. long. 



The insect that makes this delicate waxy shell, has the 

 technical name Marjarodes foriiu'cariu7n. As has already 

 been stated it is one of the scale insects, and it feeds by 

 .sucking the juices from the roots of plants by means of its 

 .slender proboscis. 



jNIany of the ground pearls, when found, are the empty 

 shells of insects which have died, but they may be found 

 attached to the roots ()f plants, and in this latter event they 

 contain the living insect. 



They are to be seen at the roots of the sugar-cane, 

 Indian corn, and of many garden plants. In Barliados, they 

 are most abundant in the ground about guava trees, 

 and in Montserrat, they are seen in clusters at the 

 base of the common wild acacia {Acacia tortuosa), a very 

 abundant shrub on waste lands in that island. 



When ground pearls occur on crops of garden plants in 

 sufficient numbers to cause any injury to the plant.s, they may 

 be controlled by saturating the soil with a weak solution of 

 whale oil soap (1 &. of whale oil soap in .5 gallons of water), 

 or a dilute solution of kerosene emulsion. 



Shield-back Bug on Cotton. 



In a letter to the Imperial Commissioner of Agriculture 

 the Hon. Francis Watts, C'.M.G., writes that a correspondent 

 in Nevis .states ' that there is a beetle, nut the cotton stainer 

 {Di/sdercus), which makes a yellow .spot on the cotton, which, 

 becoming wet, suft'uses a yellow colour over the lint.' 



Specimens of the insect have been received and prove 

 to lie a species of the shield-back bug which was found in 

 8t. Lucia on wild cotton in 1903. (See Wei-t Indian Bullrf In, 

 Tol. lY, p. 276.) 



The beetle-like aiipearance of this bug is due to the 

 fact that tlie scutellum is developed to such an e.xtent 

 that it covers nearly the whole of the upper surface of the 

 alxlouien. The family of insects [Scutelleridae) to which this 

 one belongs is not generally considered a serious pest to 

 iigriculture, and it is hoped that this one will be no exception 

 to the general rule. 



The same corres[iondent states that Dysdercris, by 

 .sucking the seed, injures it and causes the lint to be poor 

 and weak. 



The shield-back bug is of such rare occurrence in the- 

 West Indies that no remedies seem to have been tried. The 

 method in use in dealing with the cotton stainers (Di/sde>cu$) 

 ought to be efficient with this similar insect. The method 

 consists in knocking the insects otf the bolls into a bucket 

 or [lan containing kerosene and water. This can easily be 

 done when the insects are collected in numbers in the opening, 

 cotton bolls. 



TESTING SEEDS. 



In the Agricultural Jfercs (Vol. II, p. 1.53) directions 

 are given for testing the germination of seeds. 

 A descriiition is there given of a simple seed tester, concerning 

 which the following suggestions have been offered by 

 Mr. A. H. Kirby, B.A., Agricultural and Science ilaster^ 

 Antigua. 



It has been found that the cloth in which the seeds are 

 placed encourages the growth of fungi, and that the proper 

 cleansing of it after use is a matter of difficulty. By the use 

 of a porous plate, placed in the lower di.sh of water, the.se 

 difficulties are overcome. The porous plates recommended 

 by Jlr. Kirby are those manufactured by Jlessrs. Baird cfe 

 Tatlock, 14, Cro.ss St., Hatton Garden, E.G., price 2s. Gd. per 

 dozen; but any other porous material should do equally well. 



The lower plate is half filled with water, the porous 

 (jne is placed in it with its rim resting in that of the former, 

 and the whole covered by the glass plate as usual. The 

 use of flannel is, therefore, not necessary, and the employment 

 of .such a modification att'ords increased cleanliness in W(.irking,, 

 and greater reliability of results. 



IMPROVING TOBACCO BY BREEDING 

 AND SELECTION. 



Constant reference has been made in the Agri- 

 cultural Ke%cs, to the advantages which are to be 

 derived from seed selection. Particular attention has 

 been directed of late to this branch of work in 

 connexion with the cotton industry, and at present seed 

 selection ex peri men ts are being carried on by many of 

 the cotton planters in the West Indies in conjunction 

 with the officers of the Imperial Department of 

 Agriculture. 



An interesting account of improving tobacco by 

 breeding and selection is given in the Yearbook of the- 

 U.S. Department of Agriculture for 1!I04, by Archibald 

 D. Shamel :— 



During the season 1901 and 1902, Florida-grown 

 Sumatra seed was introduced into the Connecticut ^'alley^. 

 and grown extensively on the tobacco plantations cif that 

 region. The crops grown from this seed showed, however, 

 a lack of uniformity, and only about 5 per cent, of the plants 

 were tyi'ical Sumatra, the remainder being radically different 

 from the jiarent type. The 1903 crop, grown from .seed 

 saved from 1902 according to the ordinary custom of tobacco- 

 planters, showed continued variation, and a reiiroduetion of 

 undesirable types. In 1903, seed was saved from typical, 

 plants ; the flowers being protected from cross-fertilization by 

 covering them with paper bags. In 1901, the plants grown 

 from seed saved in this manner were strikingly uniform in 

 type, and closely resend.iled the [larent plants in all characters. 



The change of type is doubtless due to the influence of 

 the soil and climatic conditions, and by saving seed from 

 typical plant.s, a desirable type is secured. This must be 

 adapted to the local soil and climatic conditions. 



