Nov., '03] ENTOMOLOGICAL NEWS. 279 



The Resin-Gnat Diplosis and Three of its 



Parasites.* 

 BY L,IDA S. ECKEL. 



(With Plate XIV.) 



Finns rigida is the most common pine in this immediate 

 vicinity. July first the many empty pupa-cases projecting 

 from the lumps of resin which are abundant on the two-year 

 old (and older) parts of the pine stems, showed that the adults 

 of Diplosis rcsinicola O. S. had been escaping in numbers, and 

 attracted my attention. 



The orange-colored larvae of this species living in numbers 

 within the lumps of resin w r ere first reported by Mr. Sanborn f ; 

 the adult was described by Osten Sacken in 1871 \\ and it has 

 since been recorded from New York to Florida on various spe- 

 cies of pine. The fact that the transformations are undergone 

 within the lumps of resin were first noted by Packard ||. 



A point of primary importance to the adult insect is a safe 

 place to deposit its eggs. During the first week in July while 

 they were emerging in numbers from the lumps of resin on 

 the twigs kept in the laboratory, the}^ deposited their eggs in 

 quantities on the fresh resin provided, never upon the old 

 hardened lumps, and never upon any of the twigs or leaves. 

 No new lumps of resin appeared upon the stems, which would 

 have been the case had the Diplosis been in the habit of punc- 

 turing the bark and thus providing resin for itself. In a 

 cluster of infested pines where many fresh pupa-cases were 

 observed upon the resin, and where adults were occasionally 

 seen flying about, I cut a number of slits in the twigs. In 

 every instance (over twenty) within twenty-four hours, the 

 Diplosis had discovered and utilized the fresh resin. It was 

 interesting to see that where the pitch exuded in a spherical 

 drop, the bright orange eggs were arranged regularly around 

 il> equator projecting radially. A few of these eggs hatched 



* A study made at the Marine Biological Laboratory, Woods Hole, 

 M.iss., 1903, under the direction of Mr. C. T. Brues. 



fProc. Bost. Soc. Nat. Hist. XII, 93. 



% Trans. Am. Ent. Soc. in, 345. 



| Fifth Rept. LJ. S. Ent. Com., p. 797. See also Comstock's Manual of 

 Insects, p. 447. 



