8 



THE TOBACCO THRIPS. 



Tex., in both winged and wingless forms, on Johnson grass {Sorghum 

 halejiense) in March. It would seem, therefore, to be a general 

 feeder and widely distributed through the Southern States. 



DESCRIPTION. 



Adult. — Doctor Hinds describes the adult as follows: 



EUTHRIPS NICOTIANS Sp. HOY. 



Average length, 1.05 mm. (0.95 to 1.13 mm.) ; average breadth at middle of 

 abdomen. 0.27 mm.. (0.225 to 0.285 mm.). General color of head and thorax 

 light brown or tawny yellow-brown ; abdomen dark brown. 



Head about one and one-half times as wide as long, frequently slightly 



retracted under ante- 

 rior margin of protho- 

 rax : occiput trans- 

 versely wrinkled, pos- 

 terior margin strongly 

 thickened and darker 

 in color ; anterior mar- 

 gin slightly bi sinuate, 

 cheeks approximately 

 straight and parallel. 

 Eyes dark red in col- 

 or, not protruding, oc- 

 cupying together fully 

 one-half the width of 

 the front of the head 

 and being one half as 

 long as the head ; mar- 

 gins around eyes pale 

 yellow in color ; sur- 

 face of eyes finely fac- 

 eted and slightly pi- 

 lose; three ocelli present, well separated, posterior ones contiguous with yellow 

 borders to eyes, pale yellow in color and margined inwardly with pale-orange 

 crescents ; one moderately stout dark spine in front of each posterior ocellus ; 

 postocular spines weak and inconspicuous. Mouth cone reaching nearly to pos- 

 terior edge of the presternum, tapering abruptly; maxillary palpi slender, three- 

 segmented. Antenme inserted slightly below front margin, approximate at 

 base, about two and one-half times as long as the head and approximately equal 

 to breadth of mesuthorax ; relative length of segments : « 



1 2 :; 4 r, 6 7 8 



6.2 11.4 13.5 13.0 12.2 16.2 3.0 *4.5 



Segment 1 is rounded, three-fourths as long as broad; 2 is as broad as 1; 

 following segments about three-fourths as thick: segments 3 to 6 are con- 

 stricted at bases, becoming more stout successively. Color of segments 1 and 

 2 uniform light brown ; 3 to 5 pale yellow at bases, shading to brown at outer 

 ends, each succeeding segment from 3 to 6 becoming darker in color; 6 to 8 are 



o The number of the segment is given above the line and below it the number 

 of spaces covered upon an eye-piece micrometer by an average of the -segments 

 of 10 antennas. 



Fig. 1.— -The tobacco thrips (Euthrips nicotianse): Adult insect. 

 Much enlarged (author's illustration). 



