GEOSSING EUSCHISTUS VAKIOLARIUS AND EUSCHISTUS SERVUS. 339 



they lasted, and later in the season timothy heads and berries. The former 

 were placed in the cage in two small bunches, each containing not more than 

 five heads, cut to about 3 inches in length and the stems tightly wrapped 

 together in wet absorbent cotton. I£ the cotton is kept wet, the food will 

 keep quite fresh for three days. 



When blackberries were used, they were not plucked from the stems, but 

 small sprays with berries were selected; cut in lengths of 3 inches, and the 

 stems wrapped in wet cotton. All the leaves were carefully trimmed from 

 each spray, and only one large, or two small sprays were used in each cage. 

 The leaves must be cut off because they hide the bugs, and they are of no 

 value as food — becoming dry in a few hours. It is very important to place 

 the food in the cages in such a way that every bug can be seen at any time 

 and closely watched. When we used strawberries or cherries, we suspended 

 them by their stems from the wire tups of the cage. Frequently we used 

 the tips of young milk-weed, for we found that the bugs in captivity often 

 deposit their eggs on the under side of these leaves, though we have never 

 found any deposited on milk-weed in nature. In order to be sure 

 that all the eggs of our experiments were deposited by the bugs we 

 had under observation, no fresh food was ever placed in the cages 

 without being carefully examined to be sure that no eggs of a kindred 

 species were by any chance brought into the cages. If, however, the 

 food is changed every third day, this danger is practically eliminated, for the 

 eggs of this species require only from 5 to 7 days to hatch, and unless any 

 alien eggs were deposited on the food the same day it was put in the cage, 

 such a mistake would be very readily detected. This particular risk to our 

 experiments was reduced to a minimum in the season of 1912, for the 

 locality where we spent the summer was not only an unfavourable one for 

 Hemiptera, but the exceptional cold of the preceding winter had made the 

 locality even more than usually unfavourable. During the entire summer 

 we succeeded in finding only two specimens of Euscliistiis variolarius, though. 

 we constantly searched the wheat fields, berry bushes, &c. 



If the food is properly placed in the cages, the bugs can be kept under 

 constant observation. We have frequently watched them deposit their eggs, 

 and were able to note approximately the length of time of each mating. The 

 number of bugs in each cage must necessarily be limited, or accurate 

 observation is impossible. As a rule we never placed more than four pairs 

 in a cage, and as soon as a pair was found mating, they were transferred 

 at once to a separate cage, in which they were kept isolated for the entire 

 breeding season. Thus, for the important experiments, a single pair of bugs 

 was confined in one cage, and each mating and the deposition of each batch 

 of eggs could be accurately noted. 



The cages suitable for the adult bugs are of course not suitable for 

 the larval stages, unless a much finer wire mesh is used for the cover. 

 After various experiments we found wet chamber dishes the most satisfactory 



LINN. JOURN. — ZOOLOGY, VOL, XXSII. 29 



