OF WASHINGTON, VOLUME XIX, 1917 



ORYSSUS IS PARASITIC. 



BY H. E. BUKKE, 

 Specialist in Forest Entomology. 1 



So far as can be determined, the larval habits of the family 

 Oryssidae have never been published. Harrington (Trans. Roy. 

 Soc., Canada, Sect. IV, p. 151, 1893) says that "It has been sug- 

 gested that they are of a parasitic habit, and the actions of the 

 insects when searching for a place to oviposit very much re- 

 semble those of species well known to be parasitic." Rohwer 

 (Proc. U. S. Nat. Mus., Vol. 43, p. 156, 1912) refers to an ob- 

 servation by Dr. A. D. Hopkins which indicates parasitism. He 

 collected a pupa in an old mine of a Cerambycid in the dead 

 wood of a living Douglas spruce (Pseudotsuga taxi folia) at Port 

 Angeles, Washington,- on May 15, 1899. A male was reared 

 from this and named Oryssus hopkinsi Rohwer. 



During the past two years a number of observations have IK-CM 

 made by the various men attached to the Pacific Slope Forest 

 Insect Station which definitely prove that Oryssus is parasitic on 

 several species of the genus Buprestis and probably also on other 

 Buprestidae. 



The first of these observations was made by the writer at 

 Placerville, Calif, on March 21, 1914. A parasitic larva was 

 found in a cell in the outer wood of an old scat on one side of the 

 trunk of a healthy Douglas spruce near a young adult and a 

 large larva of Buprestis aurulenta Linn. The parasitic larva was 

 then supposed to be an Ichneumonid parasite of the Buprestis. 



On September 17, 1915, Entomological Ranger J. D. Riggs col- 

 lected at Bray, Calif., two larvae in an old aspen (Populus trcn/u- 

 loides) log. One was in the pupal cell with the fragments of a 

 beetle (Buprestis confluens Say) and the other was attacking a 

 larva of this same Buprestis. This latter specimen of parasitic 

 larva pupated on March 9, 1910, and transformed to a female 

 adult Oryssus occidentalis Cresson on March 29, 1916. 



AYhile collecting in some old weather beaten yellow pine {f'/uiix 

 ponderosa) logs near Placerville, Calif., on November 2, 1915, 

 Entomological Ranger F. B. Herbert and the writer found a num- 

 ber of naked larvae, which we took to be Ichneumonid larvae, in 

 the pupal cells of Buprestis Itirrirmfri* with the remains of the 

 larvae of that species. On March 17, 1916, three of these pu- 

 pated. One of these transformed lo an adult Oryssus occidentalis 

 on April 6, one on April 8, and one was preserved as a specimen. 



1 Branch of Forest Insects, Hnn-m of Knf omolo^y, I". S. I )ep;irt inent 

 of Agriculture. 



