16 FAEMERS' BULLETIN 606. 



insects will issue and fly to the windows. In rearing moths or other 

 insects one sometimes finds that instead of the expected specimen 

 there appears a quite different insect. This is usually an Ichneumon 

 or Tachina fly. The young of these live parasitically in the caterpillar 

 and destroy it. These parasites should be saved and when possible 

 the name of their insect host should be put on the label. 



More extended directions covering special kinds of collecting can 

 be obtained by applying to the United States National Museum, 

 Wasliington, D. C. 



COLLECTION OF ROCK AND SOIL SPECIMENS. 



While an exhaustive knowledge of geology is not essential to the 

 study or practice of agriculture, it is important that the student of 

 agriculture should be familiar with the more important types of soils 

 and the processes by which these soils are evolved from mineral or 

 vegetable sources. For this reason the pupils should collect and 

 study specimens of the more important rocks, such as granite, sand- 

 stone, and limestone, from which various t}^es of soils are formed 

 by decomposition. These rock specimens should be chipped with a 

 hammer to a convenient size and shape for handling and storing, 

 say into rectangular blocks about 2\ by 4 inches in area and 1 to 

 Ij inches thick at the center. Each specimen should bear a cata- 

 logue number or a label indicating the kind of rock and the place of 

 collection. The label itself may be pasted on a smooth surface of 

 the rock or the catalogue number may be painted on it and the de- 

 scription written in a book kept for that purpose. The specimens 

 may be kept in boxes or in trays on cabinet shelves in the school- 

 room. 



Besides these specimens the pupils slundd collect, where possible, 

 rock specimens showing e\'idences of the natural processes b}' which 

 the rocks are decomposed to form soil. Thus, rocks bearing evidence 

 of weathering, of glacial scratching, or the wearing effect of running 

 water, should be collected and properly described. 



To show the process of soil formation by the decay of vegetable 

 matter, go into the forest where there is a deep layer of leaf litter and 

 take up a section of the soil cover down to the mineral soil. Place 

 this in a glass jar, preserving as nearly as possible the positions of the 

 various strata — on the bottom the soft l)lack mold or Innnus, above 

 this the half-decomposed vegetable matter, and on top the fresh layer 

 of leaves and twigs — thus showing the A^arious stages in the formation 

 of humus. 



CoUect specimens of all the types of soils found in the vicinity and 

 (dassify them as sand, clay, silt, loam, or humus. Keep these in glass 

 j ars so that their textm'es and colors may be examined readil}-. Each 

 jar should, of com'se, bear a proper label, indicating the type of soil it 

 contains and the place where the specimen was obtained. 



