220 OHIO EXPERIMENT STATION: BULLETIN 332 



attacked with almost equal severity. The English elm (Ulmtis 

 campestris) and the weeping Camperdown elm are preferred to all 

 others. 



Distribution — At present the insect is distributed in Ohio over 

 an area not to exceed one-twentieth that of the State and is con- 

 fined to the extreme southwestern section. It was discovered first 

 at Dayton in 1904 and since that time is known to have spread north 

 as far as Troy and to the southward. Cincinnati is spotted with 

 out-breaks. In June, 1915, when a careful survey was made in Cin- 

 cmnati by the Board of Park Commissioners and the State Bureau 

 of Nursery and Orchard Inspection, the pest was recorded in forty- 

 seven sections of the city and its environs. Some persons on whose 

 premises the i)est was found said that it had been present for at 

 least 7 years, but this point is questionable. 



During the years of its residence in Dayton, it has become 

 thoroughly disseminated throughout the city and annually does 

 much harm. 



While the elm leaf beetle is a comparative newcomer in Ohio, 

 it has been in the United States about 80 years, having been estab- 

 lished first at Baltimore, Md. It now occurs in most of the eastern 

 and New England States and is thoroughly established as far west 

 as Ohio, Indiana and Kentucky, and has been reported recently from 

 the Pacific coast. 



Natural enemies. — Rigorous seasons and natural enemies un- 

 doubtedly have an important bearing in limiting this pest, since 

 unquestionably it is more abundant and destructive some years than 

 others. Of these natural controls, the one most active which has 

 come under the observation of the writer is the white fungous dis- 

 ease, Sporotrichum globuliferum. During some seasons this has 

 been noted as extremely abundant, particularly as aUacking: the 

 pupae and adults. 



This is a true fungous disease. After the spores gain access 

 to the body of the insect they germinate, sending the white, root- 

 like mycelial threads throughout the body. After the death of the 

 insect the fungous growth in many instances completely envelops 

 the body of the host, obscuring the details of its anatomy and mak- 

 ing it appear as a shapeless snow-white mass. In other examples 

 the growth but partly obscures the dead host. 



Most of the diseased insects are found in the grass and trash 

 about the base of the tree but many of the dying and dead beetles 

 lodge in the cracks of the tree trunk. A glance at Plate XXV, Fig. 

 2, will convey some idea of the activity of this agency, although the 



