1900] ENTOMOLOGICAL NEWS. 489 



The Destructive Diplosis of the Monterey Pine. 



By W. A. Snow and Helen Mills, 



Stanford University, California. 



Prefatory Note — While the late W. A. Snow was en- 

 gaged as assistant and instructor in entomology at Stanford Uni- 

 versity, he discovered and began the careful study of a new 

 species of Diplosis which was vigorously attacking the Mon- 

 terey Pines growing on the campus and in the neighborhood 

 of the University. The Monterey Pine {Pinus radiata Don. 

 and the Monterey Cypress {Cicpressus macrocarpa Hartw.) 

 are the conifers most abundantly used as ornamental trees in 

 the grounds and parks of the residents of the San Francisco 

 peninsula. The new Diplosis is the most formidable pest 

 which the Monterey Pine has to struggle against, and it is 

 still a question, despite the beneficial activity of certain para- 

 sites of the midge, whether the pest may not succeed in killing 

 many of the splendid trees of the region. The pest is ex- 

 tremely abundant, thousands of trees being attacked, and 

 most of the infested trees harboring myriads of the insects. 



Mr. Snow began his observations in November, 1897, and 

 continued them until March, 1899. Since that time Miss 

 Helen Mills, student in the department, has continued the 

 study of the pest. Mr. Snow's long-continued careful obser- 

 vation and study of the insect, resulted in the nearly complete 

 working out of its extremely interesting life history. With 

 characteristic thoroughness Mr. Snow extended his work to 

 include a valuable compilation of facts regarding the already 

 known pine midges of this country and Europe. He also 

 interested a botanist, Mr. Cannon, assistant in the University, 

 in the character of the deformation of the plant tissue, and a 

 careful study was made by Mr. Cannon of the pathologic 

 phenomena in the growing buds and needles due to the pres- 

 ence of the irritating and food taking pest ( an account 

 published elsewhere). Mr. Snow's sad death (by drowning 

 in San Francisco Bay, Oct. 10, 1899) leaves unpublished any 

 reference at all to this last undertaking in his career as a 

 student of entomology. In fairness to his memory and in fair- 



