262 Fiftieth Report on the State Museum 



the trees to a considerable extent in the course of time. For a more 

 extended notice of this insect see subsequent pages of this report (XII). 

 The injured and dying ehns were also attacked by the pigeon Tremex, 

 Tremex cohimba (Linn.), in numbers both in Albany and Troy. Many 

 of the trees showed numerous large holes made by the Tremex larvae. 

 On the trunk of one small tree, two dead females were held by their 

 inserted ovipositors, and, at the base of the tree, the remains of four 

 others were found. The parasites of the Tremex were also active. One 

 female of Thalcssa l:inator (Fabr.), "the lunate long-sting," was taken 

 while ovipositing in the trunk of an infested tree. The remains of thirteen 

 ovipositors securely fastened in the trunk of one small infested tree were 

 eloquent testimonials to the activity of Thalessa in its search for the 

 Tremex larvae. 



Natural Enemies. 



The elm-leaf beetle has so few natural enemies that they do not appear 

 to thin its ranks materially. A number of dijjterous maggots were found 

 among a mass of larvae and pupae collected at the base of a tree. There 

 was no evidence that they attacked the living forms, yet more occurred 

 than one would naturally suppose could find sustenance in the small 

 amount of decaying matter present. Unfortunately they were not 

 brought to maturity, and the species could not be determined. 



Fodisiis spinosus (Dallas) was detected with a half-grown larva of the 

 elm-leaf beetle on its extended beak, audit was also reported from Pough- 

 keepsie as preying on the insect. A larva of a lace-wing fly, Chrysopa, 

 was found in the vicinity of some dead larvK of the elm-leaf beetle, and 

 it was thought that possibly this was another of its predaceous enemies. 

 A mite was noticed near some injured eggs, but it escaped before its 

 identity could be established or its relation to the mischief ascertained. 



Many of the beetles were killed by a fungus. It affected numbers of 

 them in the breeding cages, and on some trees clusters of beetles would 

 be found filled with it. Examples were submitted to State Botanist Peck, 

 who has described the fungus as a new species in his report for 1896 under 

 the name of Sporotrichum eiitomophilum. Like the disease affecting the 

 chinch bug, caused by S. globnlifenim Speg., that of the elm-leaf beetle 

 can not develop rapidly in the absence of moisture: The affected 

 beetles were found only where there was abundant moisture, as for ex- 

 ample,- in damp crevices in the trunks of the trees, in masses on damp 

 ground and in moist breeding cages. The necessity of moisture to the 

 development of Sporotrichum entomophilum Peck, renders the disease of 

 doubtful value as a check on the undue increase of the elm-leaf beetle. 



