14 



PAPERS ON APHIDID^. 



entirely of the sexes. A viviparous female may produce oviparous 

 and viviparous females and males or she may produce only the sexes. 

 Males and females reach maturity in from 15 to 23 days. The 

 female will not oviposit without havin"^ first been fertilized and will 

 live, under these conditions, for about a month, her abdomen becoming 

 greatly distended with eggs. A female with her abdomen thus dis- 

 tendetl was dissected after death and found to contain 7 eggs. If a 



male be placed in a cage 

 with an oviparous female 

 when she reaches maturity 

 she will begin oviposition 

 in about 4 days. The ovip- 

 arous females, whether 

 in the presence of males 

 or not, apparently alwa^'s 

 maintain tJieir normal 

 position on the plant, 

 never elevating the tips 

 of their abdomens, as is 

 the case with T. graminum. 



PLACE OF OVIPOSITION. 



Wlien ready to oviposit, 

 the females crawl down 

 into the leaf sheath, which 

 is usually separated from 

 the plant stem for a part 

 of its lengtli and is some- 

 what curled, and deposit 

 their eggs in this curled 

 portion. The senior au- 

 thor has counted as many 

 as 200 eggs in such a po- 

 sition. Figure 6 repre- 

 sents such a leaf sheath 

 that has been uncurled 

 and photographed with 

 the eggs in position. In ' 

 1909 eggs were found by the thousan<ls in just such 



Fig. 7.— Lamp-chimney molting cage used in rearing aphides. 

 (Original.) 



the fall of 

 situations. 



FECUNDITY OF THE OVIPAROUS FEMALES. 



The females of this species do not u})pear to be quite so prolific as 

 those of its near relative, the destructive "green l)ug." They pro- 

 duce" only from 1 to 5 eggs, though as many as 7 eggs have been 

 taken from the bodv of a female that had not been fertilized. 



