12 BULLETIN 261 ; U. S. DEPARTMENT OF AGRICULTURE. 



NATURAL ENEMIES. 



The larvae of EuzopTiera semifuneralis are attacked by a number 

 of parasitic and predaceous enemies. Two parasitic forms were 

 reared at Winchester in 1913, which were determined by Mr. R. A. 

 Cushman, of the Bureau of Entomology, to be Idechihis sp. (PL III, 

 a) (Quaintance No. 10402) and Mesostenus thoracicus (Cress.). 

 The former was by far the more common. Of 104 overwintering 

 larvae collected in the field 14 were parasitized by this insect. This 

 proportion of parasitized specimens, amounting to 13.47 per cent, 

 indicates that the parasite may aid very materially in the control 

 of the borer. The parasitized larvae are about one-half normal size 

 and usually lack the greenish-brown color of healthy specimens. At 

 some time during the prepupal period the parasite matures, devours 

 the larva, and spins its cocoon (PL III, c). Fred Johnson, in 1905, 

 at Youngstown, N. Y., reared an undetermined member of the family 

 Ichneumonidae (Quaintance No. 574). J. H. Beattie, in 1905, at Fort 

 Valley, Ga., reared from borer larvae Itoplectis marginatus (Prov.), 

 Mesostenus gracilis Cress., and Pimpla sp. (Quaintance No. 399). 



Mr. FredE. Brooks, of the Bureau of Entomology, records rearing a 

 hairworm, probably a species of Mermis (PL III, o), from larvae of 

 the plum borer. 



Among the predaceous enemies the larva of Tenehroides corticalis 

 Melsh. has been taken feeding upon the borer. Ants and wood- 

 peckers are also important factors in reducing the numbers of this 

 insect. 



REMEDIAL MEASURES. 



As has already been stated, the plum borer will probably never 

 become a pest of more than ordinary importance, except in occa- 

 sional isolated cases. Its food habits are such that it is entirely 

 unable to establish itself upon vigorous, healthy, uninjured trees. 

 However, in common with a number of other insects it does deserve 

 some attention on account of its ability to do considerable real injury 

 where the proper conditions are presented, i. e., where trees have 

 been injured by hail, frost, or attacks of fungous diseases, and its 

 rather indiscriminate choice of food plants increases its opportunities 

 in this direction. One of the most common instances of this in the 

 observation of the writer is in the case of the collar blight of apple, 

 where the injury done by this disease is frequently supplemented by 

 subsequent attacks of the plum borer. When the ordinary precau- 

 tion of cutting away the dead bark and painting the wounded areas 

 is followed, this may be regarded as sufficient for the control of the 

 borer. Where the borer has established itself already the cutting-out 

 method is the only one that can be followed. Nothing may be 

 expected from the application of poisonous washes. 



