2 BULLETIN 1324, U. S. DEPARTMENT OF AGRICULTURE 



understanding. Many of these records are found in the extensive 

 life-history literature of entomology under titles which conceal their 

 presence. For this reason, some important contributions have prob- 

 ably been overlooked and, although a sincere effort has been made to 

 cover the ground, completeness is not claimed. 



The stimuli which determine when and where an insect will ovi- 

 posit begin to operate far back in her life and may continue to affect 

 her till the eggs are extruded. These influences are of two kinds, the 

 internal and the external, and for convenience they will be taken up 

 below in this order. 



INTERNAL PHYSIOLOGICAL CONDITIONS AFFECTING OVIPOSITION 



NUTRITION 



There is evidence to show that the amount and character of the 

 food of an insect affect the production of eggs. An adequate treat- 

 ment of this subject would necessarily involve a discussion of nutri- 

 tion and would lead beyond the limits of the present problem. It 

 is sufficient to say here that numerous authors, including Kellogg and 

 Bell (U), x Baumberger (6), Glaser (26), and Kopec (47) have in- 

 dicated that subnormal nutrition, whether due to the quantity or 

 quality of the food, may have a decided effect on oviposition. 



AGE 



Among the groups of insects which possess mature eggs upon 

 reaching the adult stage, some species, under favorable conditions, 

 lay their eggs soon after emerging, whereas others retain them for 

 a more or less extended period of time. The state of nutrition and 

 weather conditions modify greatly the extent of this period (26, 40) . 

 Xo particular attempt has been made to assemble the literature 

 on this subject and only two references are given here. Breit (10) 

 states that bombycid and noctuicl moths lay eggs soon after mating, 

 while most diurnal Lepicloptera fly around a few days before ovi- 

 2'ositing. Age has no influence upon the oviposition of Drosophila 

 mela,nogaster Meig., provided sexual maturity has been reached 

 (Adolph, 1). 



FERTILITY 



Fertility appears to be a stimulus for oviposition in some species, 

 influencing not only the time of egg laying but also the number of 

 eggs deposited. Normal oviposition of the cotton boll weevil (An- 

 thonomus grandis Boh.) apparently will not take place till fertili- 

 zation has been accomplished, but it usually begins soon after that 

 {41). Mating accelerates the oviposition of Heliothis ohsoleta Fab. 

 (62). The fertile potato tuber moth (Phthor'maea operculella 

 Zell.), according to Graf (29), oviposits within 24 to 48 hours after 

 emergence and most of the eggs are laid within 4 days. The number 

 varies from 38 to 290 eggs, the average, from 114 to 209 eggs, depend- 

 ing upon the nutrition of the female. Contrary to this, virgin 

 females oviposit in from 1 to 7 days after emergence, the average time 

 being 4.4 days. The number of eggs ranges from 1 to 51, with only 

 22.6 as an average. Unpublished observations of the writer on 



1 Reference is made by number (italic) in parentheses to "Literature cited," p. 13. 



