THE THYSANOPTERA OF CALIFOKNIA. 49 



Family THRIPID^. 



(3) Genus SERICOTHRIPS Haliday. 



Body broad and having- a silky luster, due to the presence of numer- 

 ous minute spines on the abdominal segments. Head fully one and 

 one-half times as wide as long-. Eyes large and protruding; ocelli pres- 

 ent in both sexes. Antennte eight segmented. Maxillary palpi three- 

 segmented. Prothorax much longer than the liead, without long spines 

 at hind angles. Legs, especially hind pair, quite slender. Wings 

 either reduced or fully developed; when present the fore wing is 

 broad at basal fourth, the remainder being very narrow; only one longi- 

 tudinal vein developed; fore fringe long; spines on veins numerous 

 and moderately developed; abdomen in some species strongly arched 

 and its segments broad and short; tip of abdomen conical in both sexes; 

 abdomen of male much more slender throughout. (After Hinds.) 

 To include California forms this genus must be extended as follows: 

 Head may be almost as long as wide; ocelli wanting; maxillary 

 palpi two or three seguKMited; head may be as long as prothorax; legs 

 medium stout. The three California forms now recognized are wingless. 



(i) Sericothrips apteris Daniel. 



Measurements: Head, length 0.13 ram., width 0.16 mm.; prothorax, 

 length 0.13 mm., width 0.2 mm.; length of pterthorax0.08 mm., width 

 0.26 mm.; w^dth of abdomen 0.40 mm.; total body length 0.65 to 1.0 

 mm. Antennae: 1, 18yw; 2, 39/^; 3, 45//; 4, 39//; 5, 36/<; 6, 54/^; 7, 15//; 

 8, 18yw; total, 0.25 nun. General color very dark brown, pterthorax 

 lighter, abdomen almost black. 



Head rounded in front, elevated between bases of antennas; back 

 of head cross-striate, with a spine on each side just inward from each 

 eye and several posterior to eyes; cheeks arched, sides roughened. 

 Eyes prominent, not pilose; together they occupy about one-half the 

 width of the head. Ocelli wanting. Mouth cone long, extending to 

 mesothorax, tipped with black; maxillary palpi three-segmented, 

 ^^i^t^wwce eight-segmented, basal joints widely separated; first two seg- 

 ments broadest; suture near tip of segment 6, which often makes the 

 antenna? appear nine-segmented; spines j^rominent; color quite uniform 

 brown. 



ProtJiora.r of even length with head, sides evenl}' arched, with a few 

 not prominent spines; pronotum faintly reticulate-striate; color dark 

 brown. Pterthorax not nearly so long as head, narrow in front, diverg- 

 mg posteriorly; color orange-yellow to light brown; surface marked 

 ^ith transverse reticulating wrinkles; wings wanting. Lajs moder- 

 ately stout; hind femora with spines at tip; color brown, tibia and 

 tarsi shading yellow. 



23668—07 3 



