35° Phylum Arthropoda 



color and generally spherical or slightly ovoid and are deposited in any 

 available niche or corner in the comb. About 9 to 10 days are required 

 for the eggs to hatch. The newly hatched larvae are very small — about 

 1 mm. in length and perhaps % mm. in diameter. The young larvae 

 begin to eat and to spin their webs immediately after hatching. They 

 have a tendency to congregate into a rather compact colony, and in this 

 colony they often have the power of raising their temperature some io° 

 to 15 C. above that of the environment. 



For culturing purposes, the regular milk bottle used for Drosophila 

 has been found very adaptable. Instead of using the cotton plugs 

 (which will not retain the larvae), the regular waxed cardboard milk 

 bottle tops with attached lifters have been found preferable. These fit 

 the top of the bottle very tightly and serve to prevent the young larvae, 

 which crawl up the sides of the bottles, from crawling out and leaving 

 the culture. Since mating may occur within a few hours after eclosion, 

 it is necessary to isolate the female pupae before eclosion if virgin females 

 are desired for mating purposes. This may be done very readily by 

 careful observation of the pupa cases. The wing and antennal distinc- 

 tions of the adults may be detected, by close observation, in the portions 

 of the pupa case which cover these respective parts of the adult. By 

 this means it is possible to segregate males and females before eclosion. 

 It is not safe at any time to regard a female as virgin if it is found that 

 a male is also present in the culture bottle. However, a newly hatched 

 moth always has a tuft of loose, fluffy hair-like scales on its head and 

 if these are present, it is a fairly safe indication of the moth's virginity. 



The young larvae upon hatching start eating the portion of the comb 

 known as the "midrib," which is the sheet of wax at the base of the cells. 

 They bury themselves in the wax and throw out piles of masticated wax 

 at the surface. This is a sure indication of their presence in the combs. 

 Since offspring of a given female are fairly numerous, it becomes neces- 

 sary, as the larvae grow older, to segregate portions of the colony into 

 subculture bottles; for instance, if a colony has 300 larvae present, after 

 they are about 2 weeks old, it is better to divide them into cultures of 

 about 40 or 50 larvae each. Also at this stage, it becomes necessary 

 to arrange an aerating device for the culture bottles. For this purpose 

 a special ventilator cap has been devised. It consists of two regular 

 milk bottle caps with a 1% or 1% inch hole cut through the center of 

 each. Then a piece of 40-mesh copper wire screening cut to about the 

 same size as the cap itself is inserted between the two perforated caps 

 and these layers are stitched together with some wire stapling device.* 

 This special aerating cap permits free circulation of air through the 

 bottles. The metal screen between the caps is necessary since the larvae 



♦The Hotchkiss or Bostitch letter stapler is very satisfactory for this purpose. 



