THE CANADIAN ENTOMOLOGIST. 141 



Prothorax three-fourths as long as width of head and (inclusive of 

 coxae) slightly more than twice as wide as long ; usual bristles all present, 

 long, dilated and divided at tip. Pterothorax much broader than long, 

 sides subparallel. Legs short, rather slender ; fore tarsi armed with a 

 rather long, acute tooth. 



Abdomen stout, about one and one-half times as broad as pterothorax ; 

 sides subparallel at base, converging roundly from segment 6 to tube. 

 Tube about .6 as long as head, distinctly more than twice as wide at base 

 as at apex, tapering evenly. 



Measurements : Length, 1.75 mm.; head, length .30 mm., width 

 .25 mm.; prothorax, length .18 mm., width (inclusive of coxae) .40 mm.; 

 pterothorax, width .39 mm.; abdomen, width .57 mm.; tube, length. 17 

 mm., width at base .092 ram., at apex .039 mm. Antennal segments : 

 I, 48/v. ; 2, 66/7.; 3, 66/x; 4, 68/x ; 5, 64/^; 6, 64/x ; 7, 90/x ; total length 

 of antenna, .47 mm.; width at segment 4, .037 mm. 



Female. — Forma macroptera. Differs from the brachypterous form 

 only in the presence of wings and the consequent increased development 

 of the pterothorax. 



Fore wings much broader than hind pair, sparsely fringed, and of 

 equal width throughout ; subapical fringe double for five or six hairs ; the 

 three subbasal spines knobbed ; wings of both pairs uniformly brown in 

 colour. 



lïfa/e. — Forma brachyptera. Differs from the brachypterous female 

 in the somewhat slenderer head with subconcave cheeks, as seen from 

 above, larger prothorax with a thickened median line becoming obsolete 

 before apex and base, stouter and slightly arcuate fore femora, longer and 

 stouter tarsal tooth, and the slenderer abdomen. 



Described from twenty females (two of which are macropterous) and 

 eleven males from Baldwin, Michigan, and Mahomet and Murphysboro, 

 Illinois. Specimens were taken April 17, August 16, September 4 and 

 November 7, under bark on white oak, soft maple and sycamore, by 

 Dr. H. E. Ewing, L. M. Smith and the writer. 



Type locality : Baldwin, Michigan. 



The seven-segmented antennae, elongate maxillary palpi and the 

 armed tarsus of the female distinguish this species at once from C. 

 rectangularis Hood and C. carbo7iarius Hood, the only North American 

 species properly referable to Cryptothrips. 



During the latter part of August, 1908, I found pupae of this species 

 in abundance at Baldwin, Michigan, under the loose scales of the bark of 



