February, '16] CHAPMAN AND GLASER: WILT OF GIPSY MOTH 149 



Mr. J. H. Merrill: How and when the nematodes gain entrance 

 into the insects are two questions that are yet to be solved. As the 

 nematodes were found in the intestines of S. fridentafa it is possible 

 that the nematode eggs may have been taken in with the food. As the 

 nematode in the termites were found in the head and mouth cavity, 

 these may have entered while the worms were still young. Although 

 they could enter when quite small, they could not complete their devel- 

 opment within the termite. 



President Glenn W. Herrick: Any more questions concerning 

 this paper? If not we will pass to the next paper by Mr. J. W. Chap- 

 man and R. W. Glaser. 



FURTHER STUDIES ON WILT OF GIPSY MOTH CATERPIL- 

 LARS ^ 



By J. W. Chapman and R. W. Glaser 



Introduction 



During the past two summers (1914-1915) certain questions in 

 connection with wilt of gipsy moth caterpillars have begun to clarify. 

 The published experimental results obtained during the summer of 

 1913, while helpful in interpreting many of the phenomena encountered 

 in this interesting problem, nevertheless left much in doubt. Our 

 efforts were renewed during the summer of 1914 with the hope of 

 verifying all of our previous experiments (1913) and of solving some of 

 the questions towards which w^e had begun to assume a sceptical at- 

 titude. Many interesting matters were forcibly impressed upon us 

 during the course of this study which extended over two seasons. The 

 results obtained in 1914 were discouraging although instructive. In 

 1915, however, we not only obtained data harmonizing with those 

 of 1913, but surpassing our expectations by yielding new and interest- 

 ing results. This work also clearly revealed the inadequacy of some 

 of our methods. 



In order that other investigators interested in the polyhedral dis- 

 eases of insects may be spared many of the tedious difficulties which 

 we encountered we present our work historically, and will attempt to 

 give an account of the methods which must be pursued in order to 

 ensure dependable results. This method of procedure will also have 

 the advantage of placing our new results in a proper light. 



^ Contribution from the U. S. Bureau of Entomology in cooperation with the 

 Bussey Institution of Harvard University. (Bussey Institution No. 110.) 



