Second annual Report. 



when bugs for infection later in the spring came in in large numbers, from 

 Kansas, the disease spread rapidly enough to fill the orders. Our experience 

 in the laboratory as well as in the field confirmed our beliefs of previous years, 

 that the bugs must be massed in considerable numbers before the fungus can 

 spread rapidly. 



Our infection boxes were kept in a basement laboratory, and as the heat 

 of summer increased the sides and floor were kept sprinkled, and the tempera- 

 ture was thus maintained below 85° F., and the atmosphere was compara- 

 tively humid. Nevertheless towards the middle of July, although bugs were 

 received in sufficient quantity to keep our boxes well stocked, the spread of 

 the disease began to decrease, and we had to call for contributions from in- 

 fested fields to fill our orders. It is more than probable that if boxes were 

 kept in a shaded place out of doors, for instance, in a shallow excavation in a 

 shaded bank, where the temperature might fall at night nearly to that in the 

 open, better results would be realized during the summer months. 



In three instances dead bugs with no external fungus growth were sent in 

 from infected fields with the statement that the bugs had died rapidly as if 

 from disease. The bugs ranged in age from those just hatched to adults. 

 On close inspection, light-colored patches could be made out beneath the skin 

 of the abdomen of the red larval bugs. The crushed bodies of the bugs 

 were seen to contain mycelial growths similiar to those known to have died 

 of Sporotrichum. Placed in a moist chamber, the characteristic second growth 

 of Sporotrichum was produced on many of the bugs. It thus seems that the 

 ravages of Sporoiriclmm are not always marked by an external growth of 

 fungus. However, whether the fungus can be communicated through a field, 

 or to any extent without the formation of spores outside the body, is a subject 

 for consideration. It is known that in culture media and within the bug the 

 fungus breaks up into hyphal bodies, illustrated by figures 4, 5, and 6, plate 

 II, of our First Annual Report. Whether these bodies can in any way gain 

 exit from the bug and act as the ordinary serial spores in distributing the dis- 

 ease, we have no direct evidence to show. None of the bugs sent us from the 

 fields above mentioned showed an external growth o^ Sporotrichum; yet this 

 disease was undoubtedly present throughout these fields. 



Empusa aphidis was present in our infection boxes and in some fields 

 during the summer of 1891; but although we reserved an abundance of ma- 

 terial to start this infection this spring, it did not start into new growth, and 

 no case of parasitism by this fungus came under our observation this season. 

 We have attempted during the past season to accumulate further evidence of 

 a bacterial disease of the chinch-bug. The results of our experiments have 

 been contradictory, and the question is not yet sufficiently settled to make a 

 detailed report of value. Professor Forbes has discovered that bacteria nor- 

 mally exist in the digestive tract of Hemiptera and that Micrococcus insecto- 

 rum occurs in chinch-bugs showing no signs of disease. Our observations 

 made on chinch-bugs of different ages sent in from various parts of the State 



