Dake 
AN APPARATUS FOR REARING INSECTS UNDER CONTROLLED CONDITIONS 
A paper has recently appeared which, it is believed, is of suf- 
ficient interest and importance to be brought to the attention of all 
_ workers in the Bureau of Entomology who desire to rear insects under 
controlled conditions made as nearly natural as possible. sans 
_G. U. Escherich, and is entitled "Ein Multipler Thermohygrostat mit 
Standiger Lufterneuerung [A battery of constant temperature and hu- 
_ widity chambers with continuous renewal of air], and was published in 
_ Anzeiger fiir Schadlingskunde 6: 13-14, 1930. A free translation, some-— 
what abbreviated, of this paper follows: 
For the determination of the relations between temperature, hu- 
midity, and development of insects, batteries of incubators have usu— 
ally been employed. The temperature gradient incubator of Williams 
and Kirkpatrick (Min. Agr. Egypt, Bul. 38, 1924) has also been used. 
These incubators have faults which often render exact experimentation 
difficult; for example, lack of ventilation, of light, and of constant 
_ humidity. The requirements of a good incubator for rearing insects are 

aS follows: (1) Constant temperature, (2) sufficient ventilation, (3) 
illumination from all sides, (4) constant humidity throughout the chamber. 
The principles of a new incubator that meets these requirements 
are presented here. A motor-driven blower forces air through a com- 
partment where it is heated to the desired temperature. On leaving 
the heater, the air stream is divided, one part passing through a 
dryer and the other through a humidifier. Both streams then pass into 
the rearing chamber. The rate of flow of each air stream can be con- 
trolled by a stopcock. The relative humidity of the rearing chamber 
therefore depends on the relative proportions of the wet and the dry air 
that are allowed to enter it. By properly setting the stopcocks, any 
desired relative humidity can be maintained throughout the rearing chamber. 
The rearing chamber can be opened for the renewal of food with 
little change in temperature and humidity, which very quickly return 
to their former values. 
The external heating system makes it possible to use a glass 
rearing chamber, transmitting ultraviolet light if necessary. The 
writer uses an unsilvered, double-walled glass vessel shaped like a 
bell jar. The space between the two walls is evacuated for insulation. 
This vessel stands on cork board. Tubes passing through the cork 
board admit the air to the upper part of the vessel. The air escapes at 
the bottom through a short tube in the cork board. 
A battery of these rearing chambers can be supplied with air by 
a single blower. Different temperatures in the different chambers can 
be obtained either by cooling portions of the air from a single heater 
_ or, better, by using a single heater for each temperature. A ther- 
- Mometer and hygrometer are placed in each chamber.--F. L. C. 
