262 



Phylum Arthropoda 



Waterinq 

 Tube 



otton 

 lower Pots 



J-3 



-Food 



Fig. 60. — Cross section of rearing appara- 

 tus for the firebrat for use in ovipositional 



studies. 



closed rearing cabinet has, under its fan, a large surface of brine con- 

 taining an excess of common salt, the humidity will be held near the 

 desired percentage and watering will be unnecessary. At humidities 

 lower than 70% a slender test tube of water, tightly plugged with cotton 

 batting, may be inverted on a piece of cardboard in the dish so that the 

 insects may be able to rest and moisten themselves on the damp surface. 

 Such a cage accommodates one to two hundred adult firebrats. A few 



hours' attention a month suffice 

 for their care. 



Where a careful check on food, 

 population, or oviposition is desired 

 another type of apparatus is rec- 

 ommended. It consists (Fig. 60) 

 of a culture dish, similar to the 

 above, into which are inverted 

 three clay flower-pots graded in 

 size so that the largest covers the 

 medium-sized one, which in turn covers the smallest. In order that 

 the insects may run under them the edges are supported on a thin wedge 

 of wood. Cotton batting to receive the eggs is placed between the 

 middle and outer pot. 



To segregate new generations the cotton, bearing eggs, may be trans- 

 ferred to new rearing quarters. Watering is not advised. The tiny 

 nymphs soon leave the cotton for the paper. At this temperature they 

 become sexually mature in about 3 months and gravimetrically mature 

 in about 6 months. 



Firebrats must not be grasped directly; they may be passed singly 

 without injury from one glass dish to another. Two species of greg- 

 arines, described by the author, are likely to appear in the cultures. 

 To get gregarine-free cultures it is necessary to obtain freshly laid eggs, 

 spore-free, and transfer them to sterilized, lidded, culture dishes. A ring 

 of vaseline around the outside prevents the entry of book-lice. 



The Silverfish, Lepisma Sacchar'ma 



The author has not reared silverfish extensively. Sweetman (1934) 

 states that 28 C. and 90% R. H. are satisfactory conditions for this 

 species. 



It has been found convenient to keep silverfish in apparatus similar 

 to that used for the firebrat but at a constant temperature near 28 C, 

 a relative humidity near or above 75%, and with provision for the insects 

 to have access to a small moist wick. The culture dish should be deeper 

 than that for the firebrat or nearly closed and kept in semi-darkness. 

 The papers should be more closely packed. 



