REARING MEAL MOTHS AND PARA- 

 SITIC WASPS FOR EXPERI- 

 MENTAL PURPOSES 



P. W. Whiting 

 Child Welfare Research Station, State University of Iowa, Iowa City 



FOR a number of years the writer 

 has been engaged in rearing insects 

 for genetic experiments. The Medi- 

 terranean flour-moth, Ephestia kiihniella 

 Zeller, and its parasite, Hadrobracon 

 brevicornis (Wesmael), have been found 

 good material for the purpose in view. 



There have recently been received 

 a number of requests for information 

 as to technique of rearing these insects 

 and it has therefore been thought 

 advisable to publish an account of 

 methods for the benefit of those who 

 may care to use them in their labora- 

 tories. 



Washburn (1904, The Mediterranean 

 Flour Moth. Special Report of the 

 State Entomologist of Minnesota) has 

 given an account of the moth — its 

 habits, its history, the methods for its 

 control, etc., and the writer (1919, 

 Jour, of Exp. Zool. Vol. 28, No. 3) 

 has reported on some preliminary 

 genetic experiments. 



The insect varies from three-fifths of 

 an inch to one inch in total expanse of 

 wings which are dull gray marked with 

 zigzag lines. There seem to be no ap- 

 parent secondary sexual characters, 

 but sexes may readily be distinguished 

 by external genitalia. The larvae are 



about five-eighths of an inch in length 

 when full grown. Testes are reddish, 

 showing through the creamy white 

 body and affording a ready method for 

 identifying sex in this stage. 



METHODS OF REARING THE INSECTS 



The writer's earlier work was much 

 hampered by technical difficulties. It 

 was found that, while the insect bred 

 well in mass cultures, the percentage of 

 individual pairs producing offspring 

 was very low. Experiments were per- 

 formed with different degrees of tem- 

 perature and humidity as well as with 

 various kinds of food. A series of tests 

 conducted at the Zoological Laboratory 

 of the University of Pennsylvania 

 showed that many females refused to 

 oviposit and died with abdomens filled 

 with eggs apparently normal. More- 

 over many eggs that were laid failed 

 to hatch even though the female had 

 mated. The causes of these difficulties 

 were never discovered. Success in 

 rearing the moths was finally attained, 

 however, with rolled wheat (Petti- 

 john's Breakfast Food). This appears 

 to furnish the optimum stimulation to 

 oviposition and the larvae feed well 

 upon it and grow large and fat if ample 

 floor space is provided in breeding tins. 



MALE WASPS FEEDING FROM A DROP OF HONEY 

 DILUTED WITH WATER (X8) 

 Photo by Doten (Figs. 9 and 10.) 



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