2 DEPARTMENT BULLETIN 779. 



Weather influences and the work of parasites in each locality where 

 damage has occurred generally have restricted the destructive out- 

 breaks of C. sayi to periodic intervals of two or three years. Since 

 1911, however, its activities have been reported with increasing fre- 

 quency each year in widely separated districts within its range. 

 This development indicates clearly the possibility that the species 

 may become economically more important in the future than it 

 has been in the past. 



HISTORY. 



The grain bug belongs to the rather extensive heteropterous family 

 Pentatomidae, the members of which are popularly known by the 

 expressive term of " stink-bugs." It was first authentically described 

 under the name LioderTna., subg. Chlorochroa^ sayi by Stal (1)^ in 

 1872. In the same year Uhler (2) described a species under the name 

 Pentatoma granulosa^ which later proved to be synonymous with 

 Stal's L. sayi. In 1904 Van Duzee (3) placed the species in the sub- 

 genus Chlorochroa of the genus Pentatoma. In 1909 Kirkalcly (4) 

 placed the subgenus Chlorochroa under the genus Rhytidolomia. In 

 1916 Van Duzee (7) removed Chlorochroa from Phyticlolomia and 

 raised it to generic rank, listing the species under consideration as 

 Chlorochroa sayi Stal. 



The first recorded damage by Chlorochroa sayi is found in the un- 

 published notes of the Bureau of Entomology, several farmers of the 

 upper Gila and Salt River Valleys of Arizona having reported it, in 

 May, 1903, as very destructive to wheat and barley. One farmer 

 wrote that there was an average of about 10 bugs to each head 

 of barley in his 40-acre field. After badly damaging this area 

 the insects had moved to an adjoining wheat field, these con- 

 ditions being typical for a distance of about 30 miles along the 

 upper Gila Valley. In reply to an inquiry by Dr. L. O. Howard the 

 following note was received on June 5, 1903, from Dr. R. H. Forbes, 

 director of the Arizona Agricultural Experiment Station : " We 

 have kept track of the outbreak of Lioderma sayi in Arizona. The 

 worst outbreak was upon the upper Gila River, between SafFord and 

 Fort Thomas, but a great many specimens were also to be found 

 in the Salt River Valley." In July of the same j^ear reports of dam- 

 age and specimens of the insect were received from the San Juan 

 Valley in southwestern Colorado. In 1905 and 1906 this species 

 was very numerous in the wheat fields of northern Texas, but no 

 widespread damage was reported. Dr. A. W. Morrill (6) published 

 an account of the complete loss of 13 acres of milo maize near 

 Phoenix, Ariz., in September, '1911, as a result of depredations by 



1 Figures in parentheses refer to " Literature cited," p. 34. 



