228 E. A. HARTLEY Vol. XXII, No. 8 



Length of Stage. — The larval period varies from about six 

 to eleven days, or even longer in some cases where the temper- 

 ature is low. The usual time from egg deposition until the 

 aphid host turned black, was nine to ten days. Pupation began 

 within one or two days after the host turned black, and by the 

 end of three days the last larval skin was cast and the full pupal 

 form assumed. 



It was found that it took two days longer for the larva to kill 

 and turn black an adult aphid than it did for a third instar 

 nymph, and one day longer for a first instar nymph than for a 

 third instar. This would seem to indicate that the medium 

 instars furnished optimum conditions for the development of 

 the larva, where other factors were equal. 



Pupa. 



Description. — The pupa is characteristic of the Hymenoptera 

 in general, i. e., of a form similar to the adult, with rudimentary 

 wings, and large turgid legs and antennae lying near the body on 

 the ventral side, and enclosed in transparent sheaths. When 

 first formed the pupa is almost transparent or very light yellow 

 throughout. Soon the eyes turn to a reddish brown and the 

 light yellow deepens with age until the colors of the adult are 

 reached at maturity. 



Meconia. — As soon as the pupa begins to take form, or just 

 before it sheds the last larval skin, it voids several brown bodies 

 of an oval shape. These are the characteristic meconia of the 

 parasitic Hymenoptera, and represent the total, larval excre- 

 ment that has accumulated throughout the period and dis- 

 charged at this time. 



Position. — The position of the pupa with reference to the 

 host is exactly opposite to the primary axes of the latter, the 

 same as described for the mature larva. This places the mouth 

 parts of the adult Aphelinus in a position to gnaw out the 

 emergence hole on the posterior-dorsal surface of the blackened 

 host remains. 



Length of Stage. — The average length of the pupal stage is 

 seven to eight days, but it may vary between five and fifteen 

 days, or even longer under adverse conditions. There is every 

 reason to believe that it passes the winter in this stage. 



