244 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



harrowing or dragging the fields with brush drags in an effort to dis- 

 lodge the bugs. Their efforts were in vain. In the field where the 

 parasites were so abundant on previous visits, they were very abundant 

 now, with an opportunity for our securing a lot of them. We collected 

 several thousand of the brown aphids and several more thousand of 

 the parasitized aphids which had not yet shown their parasitism. 

 Many adult parasites Avere abroad, ovipositing. After making the 

 collections of parasites, we drove south to Jefferson, where we found 

 conditions quite the same as north of Medford. We returned to 

 Wellington on a road leading directly north to Argonia. On this 

 road we found some very heavily infested wheat fields which were 

 practically devastated, and all of the oat fields south of the Kansas 

 line heavily infested and in danger of being devastated ; the parasites 

 were in almost all of these wheat fields, and in some of the oat fields, 

 but at no place were there so many as in the field one-half mile north- 

 west of Medford. 



On the morning of the 5th of May we proceeded to distribute about 

 thirty thousand parasites and seventy-five to one hundred thousand 

 aphids svhich had not yet shown parasitism, in each of three fields, two 

 oat and one wheat field, which had been previously selected because of 

 the absence of the parasites. We placed the parasitized Toxoptera in 

 three points in each field, forming a triangle, the points being about one 

 hundred yards apart. The living aphids, of course, began at once to 

 crawl upon the plants for feeding purposes. The brown parasitized 

 ones remained on the cut plants which we brought to the field. The 

 increase in the aphids in the oat fields since our first visit on the 29th of 

 April had been immense, far more than anyone could expect, fully 100 

 per cent of the plants being infested and some of them having from 

 seventy -five to one hundred aphids to the plant. On April 29, we 

 doubted there being a sufficient number of aphids on the oats to war- 

 rant an attempt at introduction of parasites. Representatives of the 

 two Kansas institutions and myself were careful to make another 

 examination of the plants for parasitized aphids immediately preceding 

 the introduction, and we all expressed the opinion that there were no 

 parasites present. Examination of the fields on the 6th of May indi- 

 cated that the hving introduced Toxoptera had crawled upon the plants 

 and many of them were turning brown ; some of the plants contained as 

 many as six or eight of the brown aphids. We continued our investiga- 

 tion in other portions of the field, where the parasites were not intro- 

 duced, but could not find a change in the situation, except the rapid 

 increase of aphids and reddening of the plants. On May 8 the condi- 

 tions in the three fields were very similar. Large numbers of the 

 introduced aphids had crawled upon the plants and had turned brown; 



