142 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



Distribution — Group A 



One of the most interesting phases of wilt besides its occurrence in 

 SO many widely different species, is its geographical distribution. We 

 have already called attention (Dec, 1913) to its almost general oc- 

 currence in the Nun moth caterpillars and silkworm in Europe^ 

 where it is commonly known as ''Polyederkrankheit" or polyhedral 

 sickness. 



The Gipsy Moth 



Glaser (1915) has shown that the wilt is present throughout the 

 entire gipsy moth infested area in New England. 



Apple Tent Caterpillar 

 Observations on the tent caterpillars which we also previously re- 

 ported have not been so general as those of the gipsy moth. However, 

 more attention was given to them the past summer and one point in 

 particular, near Lunenburg, Mass., was kept under observation. This 

 was one of the gipsy moth observation points and consisted of a tract 

 of mixed forest of perhaps fifty acres, surrounded by a dense swampy 

 growth of many acres in extent. It was in this low growth that the 

 apple tent caterpillars suffered almost complete annihilation from 

 wilt. It first appeared in a chronic form, a few dying here and there 

 in the webs. These would sometimes be spun over by the remainder 

 of the colony before others died. It became epidemic about the time 

 of complete defoliation (May 28-31, 1914), and within a few days 

 thousands of webs were covered with dead and dying caterpillars, 

 most of which were distinctly strawberry red in color. We searched 

 this area for living caterpillars at this time and only a few were found. 

 All of these when examined showed polyhedra in their blood. They 

 too died in a few days. 



Forest Tent Caterpillar 

 Though the wilt was also reported to have occurred in many places 

 m the Forest Tent caterpillar, neither of us have seen more than a few 

 typical cases from the field. Many caterpillars were sent in by the 

 field men but only a few of them proved to have typical wilt. 



The Army Worm 

 An outbreak of the army worm on Long Island, Boston Harbor, 

 during August, gave us an opportunity to determine if wilt also occurred 

 in that species. A trip w^as made to the Island through the courtesy 

 of the officers of the penal institution of the city. Several hundred 

 caterpillars were collected. Nothing resembling wilt was seen at the 



