CONTRIBUTION TO A MONOGRAPH OF THE INSECTS OF THE ORDER THYSANOPTERA INHABITING NORTH AMERICA. By Warren Elmer Hinds, Of the Massachusetts Agricultural College. INTRODUCTION. Very little attention has been given to the Thysanoptera of North America. So far as I can learn, descriptions or names of only twenty-three species have thus far (June, 1902) been published, besides three which have been recognized as previously descril)ed from Europe. Of the twenty-six species thus known in this country, four at least are certainly unrecognizable (Z;;y.r>^^y^>s' ^f/vY/c/ Packard, rhla'othrips mali Fitch, P. caryai Fitch, 7y//v> phylloxera Riley). Of the remaining twenty-two, six have been found identical with previously described species and therefore become synonyms— the large number is not surprising as many of the early descriptions are entirelv too brief to insure positive identification. Therefore only sixteen "species have hitherto been known to occur in this country. We may say that almost no systematic work has been done on the order ii/the United States, and, with the exception of a study of the '^Thripidse of Iowa," by Miss Alice M. Beach, most of the descriptions are scattered through different publications. I have endeavored to collect and present here such important facts as have already been published relating to members of this order, together with' the observations which I have been able to make. An attempt has ])een made to place the work upon a systematic basis, and in order to make the descrip-tions uniform, and thus comparative, all the existing types that it has been possible for me to see have been examined and redescribed. In all, thirty-seven species are thus treated in the systematic part of this paper. Other descriptions which it has not been possible for me to place are given together by themselves in the hope that some one more fortunate or skillful than myself may have material by which to identify them. Proceedings U. S. National Museum, Vol. XXVI— No. 1310. 79
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