﻿150 New York State College of Forestry 



injurious to stands of grass, oats, hay, etc. Hence, N. roseipennis 

 and N. rufusculus feeding on such insects must be considered as 

 economically important. The presence of nabids on plants is not 

 entirely beneficial, for it is undoubtedly true that by their habits 

 of oviposition they may, when present in great numbers, do some 

 injury. However, it is more reasonable to believe that what slight 

 harm is done in ovipositing in such material as grass-stalks is more 

 than offset by their suppression of plant-feeding insects. 



Methods 



The first specimens used in this experiment were collected on 

 June 10th. They were all females and were captured by sweeping 

 the grass with a strong net. At this early date no nymphs were 

 found, so the mature nabids had in all pi-obability hibernated over 

 winter. 



Six wooden boxes were filled with dirt, and small plants placed 

 in them. In one box was placed a raspberry slip, in another a 

 goldenrod stalk and in the remaining boxes, grass-stalks. These 

 plants were all carefully examined to avoid using any material 

 already containing eggs or harboring insects of any kind. Ordi- 

 nary glass lantern globes were then fitted with fine wire-mesh 

 remoA^'able tops and placed over the growing plants in the boxes. 



The cages so prepared were placed in a long tray at one side 

 of the insectary. This structure was screened but otherwise open 

 on three sides, giving the plants practically the same conditions 

 for growth which they had in their former habitat. 



The first specimens collected were placed on the plants on 

 June 10th. Every morning each plant was examined and the 

 habits of the nabids observed. This was especially for the purpose 

 of noting when the first eggs were laid so that a careful record 

 of oviposition could be kept. Every second day about half a 

 dozen aphids or other small insects were placed in each cage. By 

 the thirteenth of June six cages were in operation, each containing 

 one female, and two containing male and female. 



On the sixteenth of June the females began to oviposit, and since 

 the grass-stalks seemed most preferred, the other plants were dis- 

 carded, grass-stalks replacing them. One raspberry slip also was 

 found to contain many eggs and was set aside. 



Because of the peculiar habit of the female in laying her eggs, 

 it was often difficult to distinguish the eggs oviposited at a certain 

 time from others laid in among them perhaps the next day. The 

 most accurate way of keeping this data was by numbering the 

 sides of the boxes and designating the eggs by their position on 

 the stalk in relation to the number on the side of the box. 



On the thirtieth of June the specimens were again changed to 

 new plants, since the egg-laying period was drawing to a close 

 and the grass-stalks were well filled with eggs. This allowed 

 a closer study of the hatching eggs and also of the habits of the 

 mature nabids, which still laid a few eggs. 



