THE PEAR THRIPS. 11 



Adults may be present in an orchard for a few days and then 

 suddenly almost all disappear. This is explained by their habits of 

 migration as evidenced by the following observations: In a certain 

 pear orchard which had been kej)t under daily observation for a 

 week or more thrips had been a])undant in blossoms and buds until 

 suddenly one day all seemed to have disappeared. ITpon closer ex- 

 amination, however, they were foiuid congregating and walking 

 around on the larger branches. This was about .3 o'clock in the after- 

 iu>on. On the following morning hardly an individual could be found 

 in the orchard. This manner of fhght seems to be distinctly migra- 

 tory. Thrips often leave their places of feeding just before sunset 

 aiid hover around and over and later settle back on the same trees. 

 This mode of flight is decidedly difl'erent from the migratory one. 

 It occiu's only at evening, and the writer has never seen tlu> pear 

 thri})s in flight during the morning or during th(> middle of the dav. 



DKSCHIPTIOX. 



Euthrips pyri Daniel. 



Mtasuirments: Head, length 0.13 mm., width 0.15 mm.; prothorax, length 0.13 

 mm., width 0.2 mm.; mesothorax, width 0.28 mm.; abdomen, width 0.31 mm.; total 

 length 1.26 mm. Antennae: 1, 33//; 2, 45/(/; 3, 63//; 4, 54//; 5, 33//; 6, 66//; 7, 9//; 

 8, 12//; total, 0.31 mm. Color dark brown, tarsi light brown to yellow. 



Head slightly wider than long, cheeks arched, anterior margin angidar, back of head 

 transversely striate and bearing a few minnte spines and a pair of very long prominent 

 spines between posterior ocelli. Eyes prominent, oval in outline, black with light 

 borders, coarsely faceted and pilose. Ocelli are approximate, yellow, margined 

 inwardly with orange-brown crescents, posterior ones approximate to but not con- 

 tiguous with light inner borders of eyes. Mouth-cone pointed, tipped with black; 

 maxillary palpi three-segmented; labial palpi two-segmented, basal segment very 

 short. Antcnn-cr eight-segmented, about two and one-half times as long as head, 

 uniform brown except segment 3, which is light brown; spines pale; a forked sense 

 cone on dorsal side of segment 3, with a similar one on ventral side of segment 4. 



Prothorax about as long but wider than head; a weak spine at each anterior and two 

 large, strong ones on each posterior angle; other spines are not conspicuous. Mcso- 

 thorar with sides evenly convex, angles rounded; metanotal plate with four spines 

 near front edge, inner pair largest. The mesonotal and metanotal plates are faintly 

 striate. Legs moderately long, uniform brown except tibite and tarsi, which are yel- 

 low. Spines on tip of fore and middle tibia' weak; several strong spines on hind 

 tibia\ Wings present, extending beyond tip of abdomen, about twelve times as long 

 as wide, pointed at tips; costa of fore wings thickly set with from twenty-nine to 

 thirty-three quite long spines; fore vein with twelve or fifteen arranged in two groups 

 of three and six, respectively, on basal half of wing and a few scattering ones on distal 

 part; hind vein with fifteen or sixteen regularly placed spines; costal fringe on fore 

 wing about twice as long as costal spines. 



Abdomen subovate, tapering abruptly toward the ti]) I'mni iln- cighih segment; 

 longest spines on segments 9 and 10; alidomon uniform l)ro\vii. conncclivc tissue 

 yellow. 



Redescribed front many specimens, including sc\cral cotypes from Miss Daniel. 



Mule unknown. 



Food plants: Apricots, apples, almonds, cherries, tigs, grapes, pears, prunes, plums, 

 walnuts. The insect is found mostly on deciduous fruits. 



Habitat: San Francisco Bay region, California. 



