BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [120] 



taken, the mortality will frequently amount to 50 per cent of tlie speci- 

 mens. Mr. H. Bakhaus, of Leipsic, tkus describes a device wMcli is sub- 

 stantially the ba^e of the vivarium shown on page 114. 



"The base consists of a round plate of strong zinc, with two vertical 

 rims, an inch high, placed one within the other, an inch apart, and 

 soldered to the basal plate so that the outer one is water-tight. The 

 inner rim must be perforated with small holes as close to the bottom 

 as possible. The space inside the inner rim must be filled with fine 

 sand, on which the pupte should be laid. The si)ace between the two 

 rims is then filled with water, which, finding its way through the 

 holes in the inner rim to the sand, causes the necessary moisture. 

 Over the whole is put a bell-shaped cover of wire gauze, which must fit 

 tightly over the outer rim. In this receptacle the pupte remain un- 

 touched, and receive fresh moisture, as above indicated, if required by 

 the drying of the sand." 



The hardy pupae of most Noctuids and Bombycids, as well as those 

 of many Eophalocera, may be handled with little danger, but other 

 species, if handled at all, or if the cocoons which they make for themselves 

 are broken, can seldom be reared. Constant ijrecautions also must be 

 exercised in the care of the soil and the breeding cages. One of the 

 great drawbacks is the presence of mites and thread worms (Entozoons)^ 

 etc., which affect dying or dead pupae and larvae in the soil. They also 

 affect living specimens and are capable of doing very considerable 

 damage. To free the soil of them it is necessary at times to allow the 

 earth to become dry enough to be sifted, anc^ then after removing the 

 I)upte submit it to heat sufficient to destroy any undesired life there 

 may be in it. 



The Insectary. — Up to the present time the work of rearing insects has 

 been largely confined to the breeding cage and breeding jar, already de- 

 scribed, which have been kept in the rooms of the investigator. The 

 advantages of having a special building for this purpose are at once 

 apparent and need not be insisted ui3on. One of the best establish- 

 ments of this kind is that of the Cornell University Experiment Station, 

 which was fully described in Bulletin No. 3, of that station, ]S"ovember, 

 1888. The Kansas Experiment Station has a similar building, and one 

 has recently been built for the use of the Entomological Division of-the 

 United States Department of Agriculture. The insect- breeding house,, 

 or insectary, should comprise a building having workrooms, or labo- 

 ratories, for microscopic and general work in the study and preparation 

 of specimens, and also a conservatory for the rearing of specimens and 

 the growth of plants, and, where applied entomology is concerned, 

 special rooms for the preparation and the test of insecticides. The 

 building proper should also have a basement storage room for hiber- 

 nating insects. The laboratory should be fitted with all the apparatus 

 used in the study of insects, including microscopes and accessories and 

 a dark-room for photographic purposes. 



