b THE PEAR THEIPS. 



size and prominence to those at the angles of prothorax, the others are small; ptero- 

 , thorax yellow-brown, transversely wrinkled. 



Wings present, extending slightly beyond abdomen, about twelve times as long as 

 wide, pointed at ends ; surface of wings thickly covered with minute brown spines ; 

 both longitudinal veins and costa of fore wings thickly set with quite long, brown-colored 

 spines, placed regularly on costa and hind vein; costa has from 29-33 spines, fore vein 

 12-15, and hind vein 15-16; veins not prominent; costal fringe of fore wings about 

 twice as long as costal spines. 



Legs moderately long, scarcely thickened ; femora and all except the terminal part 

 of tibia brown ; terminal part and tibiae and tarsi yellow, a double row of twelve strong 

 spines on the inner side of hind tibia, several inconspicuous spines on fore and middle 

 pairs. 



Abdomen about two and one half times as long as width of mesothorax, cylindrical 

 to eighth segment, then abruptly pointed. Spines on sides and around tip of abdomen 

 dark brown, conspicuous ; those on last two segments are long and approximately equal. 

 Color of abdomen dark brown, connective tissue yellow. 



OCCURRENCE AND DISTRIBUTION. 



We know now that the pear thrips is not confined to Alameda County, 

 where it was first found, and to the Santa Clara Valley. We have 

 learned, through Prof. C. W. Woodworth of the University of California, 

 that during the present year it has been injuring fruit trees around 

 Vacaville and Suisun and along the Sierra foothills. During a recent 

 trip through the southern part of California, I learned of its presence 

 in Los Angeles County. Other than this we do not know how wide- 

 spread the pest is, nor where it originated, whether here in California 

 or whether it is an introduced species. The insect may have originated 

 on some of our wild plants, such as the wild plum or cherry, and later 

 as our valleys have developed^ into large fruit-growing districts, the 

 insect, finding more and better food, may have changed its feeding 

 liabits from wild to cultivated plants. This would be a not unnatural 



;'::5 change. On the other hand, it may have been imported and here find- 

 ing conditions favorable without any effective natural insect enemies 

 or fungous diseases, it has spread and developed accordingly. 



Evthrips pyri first came particularly to the notice of the Santa Clara 

 County public in February, 1904, when several orchardists noticed that 

 their trees were not coming into blossom in the usual way. The buds 

 appeared blasted, turned brown and fell without opening, and trees 



_^ which did blossom dropped their petals early. In either case the trees 

 looked much as though a hot blast had passed over them. This as 

 orchardists remember, had happened in places for several years and 

 the injury had not been explained. Last year an attentive observer 

 actually found certain tiny insects in the blossoms, and the cause of 

 the injury was at once apparent. The insects were brought to the 

 attention of Mr. Ehrhorn, former Horticultural Commissioner of the 

 county, now first deputy State Horticultural Commissioner, who deter- 

 mined them to be thrips. Immediately" on learning of the damage 



