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Annals Entomological Society of America [Vol. VIII, 
In view of the limited nature of the morphological studies 
of former workers, specimens of as many species of thrips as 
possible were secured for this work in order that an extensive 
view of the conditions in the order might be observed. Twelve 
or more species were used and of these the following nine were 
identified: (1) Heliothrips femoralis Reuter, (2) Frankliniella 
tritici Fitch, (3) Thrips physapus Linne, (4) Cephalothrips 
yucce Hinds, (5) Haplothrips verbasci Osborn, (6) Thrips 
tabaci Lindeman, (7) Chirothrips manicatus Haliday, (8) 
Anaphothrips. striatus Osborn, (9) Limothrips cerealium 
Haliday. 
The first five species in the above list are very abundant in 
the vicinity of Urbana and as living material was necessary 
for certain methods of preparation used, the most of my obser- 
vations were made on these. Fortunately these have proven 
to be typical and also comparatively easy to dissect and section. 
Heliothrips femoralis was present thruout the year in its 
nymphal and adult stages in the city and university green- 
houses. Cephalothrips yucce was found thruout the year 
between the closely appressed leaves of the crown of the yucca 
plant, Yucca filamentosa. Its nymphal stages are abundant 
from April to December. Only the adult stages of the following 
were found: Frankliniella tritici occurs in great numbers’ 
in the flowers of peonies, roses, composites, etc. Thrips 
physapus was very abundant in the flowers of dandelions and 
Haplothrips verbasci can be secured the year around on mullein. 
Of the above five genera, Heliothrips, Frankliniella and Thrips 
belong to the suborder Terebrantia while Cephalothrips and 
Haplothrips belong to the suborder Tubulifera. The nymphs 
of Heliothrips and Cephalothrips and the adults of all five 
species mentioned have received similar treatment and 
observation. 
Thruout the following discussions the structures as they 
exist in the generalized Terebrantia are considered first and 
the Tubulifera are compared with them. The generic names 
have been used in the different discussions and on the figures 
since only a single species of each genus has been considered. 
The term nymph is used in the following pages to designate 
the feeding, active, immature stages. In most cases only the 
older nymphs were used, however, a few observations were 
made on the early instars, but these did not differ from the 
