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



puncture holes in Aphis bakeri, in which the actions are described 

 in some detail. 



A number of the above cited observations have been ver- 

 ified, by the writer, on Aphelinus semiflavus, and additional data 

 have been secured on this interesting feeding habit. 



These parasites confined in glass vials or other receptacles 

 without food or water were noticed to live but two or three 

 days at most; while those among aphids lived a much longer 

 time (two weeks or more). This species had also been observed 

 feeding at the puncture holes made by the ovipositor in aphids. 

 In addition to this aphid-feeding habit, the writer was interested 

 to know whether they fed on any other substance, and if so, 

 how long they would live on the various kinds of food that 

 might be available. This point was thought to have consid- 

 erable bearing on methods of handling and transporting species 

 to be used in an economic way for the suppression of injurious 

 forms. 



Several experiments were undertaken to test out the effect 

 of various foods on the length of life of adult Aphelini. Spec- 

 imens emerging at the same time were placed in cages as follows : 

 One lot on dock {Riimex obtusifolius) only, in a lantern globe 

 cage; another with four or five large aphids not yet producing 

 young; still another on a dock plant to which leaves covered 

 with honey-dew were added every other day; and lastly, a lot 

 on a plant with honey solution added every day. All were con- 

 fined in lantern globe cages with growing dock plants in room 

 107 of the Botany and Zoology Building. The results appear 

 in Table III. 



Some careful observations were made on Aphelinus semi- 

 flavus in the act of feeding at the puncture holes made by its 

 ovipositor in aphid nymphs. To confine the specimens so that 

 they could be easily observed under a binocular microscope, 

 two hollow ground slides were used with the aphids and parasite 

 in the space between them on a bit of leaf. Four or five 2-instar 

 nymphs were thus enclosed with one female Aphelinus. Ovi- 

 position began immediately after they were placed together, 

 and was repeated several times in the same aphid, after which 

 the victim was noticed to droop down in a sickly condition. In 

 this state the parasite approached and carefully examined the 

 aphid with its antennae. Being apparently satisfied, it placed its 

 forefeet on the victim's back and its mouthparts to the puncture. 



