260 Phylum Arthropoda 



in this province may be kept alive for some time in a mass of damp 

 leaves from the forest floor; I have not succeeded in getting them to 

 breed in captivity. Machilis maritima covers much territory on the rocky 

 seashore; it dies quickly in confinement. Of the four (unnamed) species 

 in the dry interior of British Columbia, only one may be kept in cages. 

 It frequents deep moss from under timber in gullies. A square foot of 

 this moss in a large tin will keep a small colony alive for several weeks. 



Lepismidae. Thermobia domestica is the easiest of all to rear. Any 

 long box or laboratory drawer will do if it has a close-fitting lid and has 

 one end against a hot radiator, to ensure a temperature, at one end, of 

 90 to ioo° F., and a gradient dropping to 8o° F. at the other. Eggs are 

 laid at about 80 ° to 85° F. 



I have kept one colony going for ten years in a large, 27-drawer incu- 

 bator. The shell of the incubator is double- walled with celotex (corn 

 stalk board), with a 4-inch air space between walls perforated at in- 

 tervals with 1 -inch holes. The back has a baffle-plate of thin asbestos 

 board heated with a battery of six large carbon lamps, two of which dip 

 into a large pan of water. The ends of all drawers touch the asbestos 

 board at the back, whence they get the necessary heat. The drawers are 

 roughly 27 x 10 x 7 inches, open on top with a 2 -inch wide strip of cellu- 

 loid cemented on the edge all round and overhanging inwards. 



Lepismids cannot walk on smooth surfaces, and so cannot escape from 

 the open drawers. On the floor of each drawer is a dissecting pan or 

 other shallow tin tray i-inch deep, full of sand which is kept always damp. 

 At 2-inch intervals on the floor are flat 2 -inch squares of cotton-batting 

 blackened with India ink and dried. 



Eggs are deposited in the cotton wool at various distances from the 

 heated rear end, and the nymphs find adequate shelter under it until the 

 third instar when they venture further afield. Food consists of whole 

 wheat meal or plain flour; at intervals of 2 weeks I put in a teaspoonful of 

 very lean beef or veal, thoroughly dried on a radiator and pulverized. 

 This meat powder is a great attractant. All food must be dry. 



Watch out for overcrowding, or disease will wipe out the whole colony. 

 Five hundred individuals can live in a drawer of the dimensions above ; 

 two or three hundred is better. There is one brood per year. Breeding 

 occurs at irregular intervals. 



Lepisma saccharina colonies have been kept in the incubator for eight 

 years. They require less heat than T. domestica and more moisture. In 

 addition to the tin tray of damp earth or sand, I use a heap of small 

 squares of shingle separated from each other alternately, by a match. 

 This gives narrow crevices in which the colony spends most of its time, 

 especially the young nymphs. On top of the cedar shingles is a small 

 saucer of raw earthenware which is filled with water every week, thus 



