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



and probably are not capable of sustaining it in flight at all. 

 On the other hand, the legs are well developed. 



The above evidence would tend to discredit Aphelinus where 

 rapidity of dispersion was a prerequisite for efficiency, but Mr. 

 H. S. Smith and Harold Compere ('20) have pointed out in 

 their work with Aphycus lounsburyi, an imported parasite of the 

 black scale in California, that this is a trait in the parasite's 

 favor where it is for local distribution by man. 



Reactio7i to Light. 



The adult Aphelinus is slightly positive to light, but- it does 

 not become quiescent in darkness, as shown by several exper- 

 iments to determine the effect of light on oviposition, which 

 will be taken up in detail under that heading. 



Oviposition. 



When the attention of Aphelinus is directed toward an aphid 

 for oviposition, it moves with extreme precaution and delibera- 

 tion; approaching very slowly and steadily, swaying from side 

 to side and feeling forward with the antennae. Just before the 

 antennae touch (in some cases they do touch) , it halts its forward 

 progress, sizes the situation up carefully from short range, 

 obliques slightly, turning the head toward the aphid with a 

 last parting look as if to make sure of the aim, position, etc., 

 and then suddenly faces about, rising well up on the legs, 

 thrusts the ovipositor out and downward with three or four 

 quick backward strokes toward the victim. In the majority of 

 cases, these miss the mark, either by the aphid moving or 

 through poor aim. Usually they fall short and the point of the 

 ovipositor is brought down on the substratum on which the 

 aphid rests. If the host is in an advanced stage, the parasite 

 may have difficulty in piercing the integument. In either case 

 after about three or four thrusts, it will turn and repeat the act, 

 or crawl away in search of a more favorable victim. However, 

 if successful, it remains in position, standing well up on the legs, 

 the ovipositor thrusts out and downward, with just the tip 

 inserted in the host. (Plate I, Fig. 2). This position is often 

 maintained for several minutes. In fact, some were observed to 

 last as long as fifteen minutes, and repeated twice in succession 

 for a like period without depositing a single egg. 



