GENETIC STUDIES ON FLOUR-MOTH 417 



Lowell stock. A box of "Cream of Wheat" from Lowell, Mas- 

 sachusetts, was found in July, 1916, to be infested. 



Calvert stock. A large tin box of flour heavily infested was 

 given me by Professor Calvert in the fall of 1916. 



Washington stock. A culture was obtained from the Bureau 

 of Entomology, Washington, D. C, in June, 1916. 



Strain A of TVashington stock. A pair of moths was isolated 

 from the Washington stock on July 11, 1916. The female was 

 probably not virgin. A mass culture was made from the progeny. 



During July and the first part of August, 1916, the moths 

 were bred and studied at the Marine Biological Laboratory, 

 Woods Hole, Massachusetts. From then until the end of Sep- 

 tember they were left in mass cultures. The results described 

 below are from matings made at the Zoological Laboratory of 

 the University of Pennsylvania. 



C. Technique 



Various methods of rearing the moths have been tried. It has 

 been found convenient to use glass candy jars with an inside 

 measurement of 4^ inches in height by 4 inches in diameter. A 

 small amount of cereal is placed in the jar and the etherized 

 moths are set upon this. If progeny are produced, as may be 

 easily determined by the appearance of webs, more cereal is 

 added. 



Pupation normally occurs in silken tubes spun in the cereal, 

 but overcrowding or lack of food sometimes causes the cater- 

 pillars to wander. The moths emerge and rest upon the glass. 

 They do not fly unless disturbed, so that it is an easy matter to 

 collect them in a shell vial. After several moths have been thus 

 secured they are turned into a wide-mouthed bottle containing 

 ether fumes. The etherized moths may be studied under a 

 binocular and sorted out for recording and pairing. 



Once fertile eggs have been obtained from a pair, there is little 

 difficulty in rearing the larvae. The jar has but to be set in a 

 warm, humid place. The adult moths are, however, extremely 

 sensitive to environmental conditions. Mating apparently occurs 



