THRIPS 



527 



of the Order it would appear that Thysanoptera are insignificant, 

 as less than 150 species are known. Thrips have been, how- 

 ever, very much neglected by entomologists, so it will not be a 

 matter for surprise if there should prove to be several thousand 

 species. These Insects 

 present several points 

 of interest ; their 

 mouth - organs are 

 unique in structure : 

 besides this, tliey ex- 

 hibit so many points 

 of dissimilarity from 

 other Insects that it 

 is impossible to treat 

 them as subdivisions 

 of any other Order. 

 They have, however, 

 been considered by 

 some to be aberrant 

 Pseudoneuroptera (cf. 

 Vol. v.), while others 

 have associated them 

 with Hemiptera. Both 

 Brauer and Packard 

 have treated Thysa- 

 noptera as a separate 

 Order, and there can 

 be no doubt that this 

 is correct. Thysano- 

 ptera have recently been monographed by Uzel in a work that is, 

 unfortunately for most of us, in the Bohemian language.^ 



The antennae are never very long, and are 6 to 9 -jointed. 

 The head varies much, being sometimes elongate and tubular, 

 but sometimes short ; it has, however, always the peculiarity that 

 the antennae are placed quite on its front part, and that the 

 mouth appears to be absent, owing to its parts being thrust 

 against the under side of the thorax and concealed. Their most 

 remarkable peculiarity is that some of them are asymmetrical : 

 Uzel looks on the peculiar structure, the " Mundstachel," tn, m 



' Monogrctphic der Ordnung Thysanoptera, Kbniggratz, 4to, 1895. 



Fig. 253. — Idoloihrips s^iedrum. Aiistralia. 



