226 
IOWA ACADEMY OP SCIENCES. 
at sides and toward apex; narrow basal band on segments 2-7, expanding 
laterally and broken up into spots, one of which is more conspicuous 
than the others, brown. 
Femora and tibiae dusky or brownish on upper surface, pale on lower 
surface and at base, the latter also pale at tip; anterior wings dusky yel- 
lowish; spines brown. 
By its seven-jointed antennae. T. lactucse is allied to T. tabaci, Lind., 
but it is more heavily marked with brown; the color of the intermediate 
joints of the antennae is darker; the antennae and the ocelli more approx- 
imate; the ocelli more conspicuous and farther removed from the anterior 
margin of the vertex; the prothoracic bristles larger and less uniformly 
distributed, being entirely absent from two discal areas; those at 
posterior angles, longer; proximal spines on cubitus arranged in a single 
group. 
Described from numerous specimens taken on wild lettuce 
in October, November and March, at Ames, Iowa. 
T. lactucce bears some resemblance to T. tritici in size and 
general color, from which it may be easily separated by the 
fewer antennal joints, less rectangular head, less widely sep- 
arated ocelli, absence of long bristles at anterior angles of 
prothorax, less numerous cubital spines and their arrangement 
in groups, absence of spines at apex of intermediate and 
anterior tibia© and inner margin of posterior tibia©. 
From T. striata it may be known by the difference in number 
of antennal joints, absence of annulation on sixth joint, pres- 
ence of longer and more numerous spines and bristles. 
Thrips pallida n. sp. 
Female: Length 1.12 mm. Color varying from white to pale yellow. 
Antennae, beyond basal joints, more or less dusky. Head small, eyes large. 
Anterior wings partially trifasciate. Bristles on anterior portion of body 
long and slender. Prothorax characterized by the presence of a long 
bristle on the middle of each lateral margin in addition to those at anterior 
and posterior angles. 
Head small, about as long as broad. Occiput very short, not more than 
one-third the length of the head. Eyes dark red-brown, very large and 
prominent, sparsely and feebly pilose. Vertex narrow, elevated, trans- 
versely convex, ascending toward the anterior margin, the latter arcuate. 
Ocelli in middle of vertex, nearly colorless, their inner margins white, con- 
tiguous anteriorly. Ocellar bristles as long as the head. Front prominent, 
bearing a row of recurved bristles above insertion of antennae. Mouth 
parts short, nearly symmetrical. 
Antennae approximate; the two basal joints the stoutest; joint 1 semi- 
globose, one-half the length of joint 2; the latter is stouter than the former, 
barrel-shaped, equal in length to joint 5, and a little shorter than joints 3 
or 4; these are robust, subequal in length and broadly obovate, the pedi- 
cel of joint 3 is short and slender; joint 5 is oval and less robust than the 
two immediately preceding; the remaining joints are sessile, together form 
