2 BULLETIN" 438, U. S. DEPARTMENT OF AGRICULTURE. 



Matthew Cooke ( 1 ) ^ in the year 1881. At that tnne it was reported also 

 from Natoma and Santa Clara, Cal. In the spring of 1909 it was 

 quite common in the vicinity of Stanford University, Cal., and in 1911 

 it was a pest in Tehama Comity, Cal., besides being generally dis- 

 tributed throughout the central counties, both on the coast and in 

 the great interior valleys of Sacramento and San Joaquin? (3) As to 

 neighboring States, Prof. H. F. Wilson, of the University of Wisconsin, 

 in a letter reports the insect attacking pear foHage in Oregon (1913); 

 Dr. A. W. Morrill, State entomologist of Arizona, states in a letter 

 that Arizona is free from the insect (1913) ; Prof. C. P. Gillette states 

 that the insect does not appear to Hve in Colorado. In Washington 

 it was found in pear orchards in the Wenatchee VaUey in 1914 and 

 1915, being particularly abimdant in an orchard about 6 miles from 

 Wenatchee, but careful inquiry did not lead to the discovery of other 

 orchards having more than a scattering infestation. 



Mr. C. L. Marlatt, in describing this insect, states that Dr. J. A. 

 Lintner, former State entomologist of New York, reported an unde- 

 termined sawfly larva as being injurious to pear in a nursery at 

 Geneva, N. Y., in May, 1894. Mr. Marlatt says (2)^ it is probable that 

 this is the same species, but as it has not been reported since, so far 

 as known, the identification of the Geneva specimens remains doubt- 

 ful; however, the collection of a specimen at Brockport, N. Y., indi- 

 cates that it may be found in the East, 



POSSIBLE ORIGIN. 



An attempt was made in Washington to ascertain the natural 

 hosts of the pear leaf-worm. The fact that it is found in various 

 locahties throughout a range of a thousand miles would indicate that 

 it is a native species. Two wild plants related to the pear are to be 

 found in the vicinity of Wenatchee, Wash. These are the service 

 berry (Amelanchier cusickii Fern.) and the thorn apple (Crataegus 

 hrevispina Dougl.). Plants of both species were searched carefully 

 for larvae of the sawfly several times in May. Nothing was found 

 on the service berry, but the thorn apple yielded a number of green 

 larvae very similar to those on pear. They differed, however, in 

 being a more shiny green, and in having scattered brown dots laterally 

 and dorsally on the thorax. A number of these were reared, but the 

 adults have not yet emerged. It is very probable that they belong 

 to a distinct but closely related species. 



Nearly full-grown larvae of the pear leaf-worm were placed upon 

 twigs of both the service berry and the thorn apple. Those on 

 the former fed a little, but soon dropped off and died, while the 

 larvae on the latter at once began to feed, and several of them matured 

 and spun cocoons. From this it may be inferred that the pear leaf- 



1 Figures in parenthesis refer to "Bibliography," p. 23. 



