New York Agricultural Experiment Station. 481 



during the latter part of May and the middle of June. June 17, 

 the writer had a good opportunity to watch some of these minute 

 parasites in the act of oyipositior.. They were flying or walking 

 nervously about the infested leaves as if looking for just the 

 right lice upon which to deposit their eggs. The female appa- 

 rently selects a suitable part of the body of her victim upon which 

 to place an egg, straightens her legs somewhat so as to raise her 

 body, and brings the tip of the abdomen forward between them as 

 far as necessary. In doing this the abdomen may be lengthened 

 to twice its natural length and extended half its length or more 

 beyond the head. The lice usually place the eggs upon the ab- 

 domen of the plant louse, but this is not always the case. Upon 

 one occasion out of six parasites under observation, four placed 

 the egg upon the abdomen, one upon the thorax and one upon 

 the head. In all of these and many other cases under observation 

 the plant lice upon which the eggs were laid were not more than 

 half grown. 



The time required for the eggs to hatch and the insect to 

 mature was not observed. Both larvae and pupae were dissected 

 out of parasitized lice. A drawing of the former, greatly en- 

 larged, is shown at Plate XXVI, fig. 4; of the latter ait fig. 5; 

 and photographs of the mature insect at figs. 2 and 3. 



June 18, a number of the parasites hatched from specimens 

 kept in the laboratory. In all the cases observed the developed 

 parasite was on its back within the body of the louse, with the 

 head near the posterior extremity. When ready to emerge the 

 imprisoned insect begins to cut through the walls of the abdomen 

 with its jaws, cutting a round opening large enough to admit 

 its body. As a rule the piece is not cut clear around, thus leav- 

 ing a hinge as shown at Plate XXVI. fig. 6. It takes but a very 

 short time for the parasite to make its way to liberty, about four 

 minutes being the time required for those under observation. 



Other species bred from Mijzus riUs by the writer are Isocratus 

 vulgaris Walk, and Pachijneuron aphid ivorus* Ashm. These spe- 

 cies were not abundant. 



•Tdentifled by Mr. William Ashmead. 



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