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JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



from this circular band to the left eye (PL 16/figs. 1, h and 2, b) and a 

 rudiment of one under the right eye (PI. 16, figs. 1, a and 2, a). At each 

 side of the head and extending a short way down the side of the mouth 

 cone is a peculiar curved spine which may possibly serve as a strength- 

 ening rod to the side of the cone (PL 16, fig. 2, d). The suborder 

 Tubulifera has the connection with the eye wanting. 



The general makeup of the mouthparts of the different species is quite 

 similar, the greatest difference occurring in the shape of the parts in 

 those species where the cone is blunt instead of sharp. In the former 

 case, the separate parts are heavier and broader and necessarily 

 shorter. There is also some difference in the number of segments 

 of the labial and maxillary palpi, as will be noted later. The mouth- 

 parts of the young are similar to those of the adult, though less strongly 

 chitinized. 



As to the asymmetry of the mouthparts, I have adopted Garman's 

 views and consider the unpaired organ on the left side as the mandible. 

 The labrum and the clypeus also show asymmetry and these will be 

 discussed separately. 



Labrum. — The labrum (PL 16, fig 1, I) forms the front of the cone 

 and is asymmetrical in all the thrips. It is composed of two segments 

 closely united and is distinguished from the clypeus (PL 16, figs. 1, 

 c and 2, c) by a membranous connection. It is long, slightly curved 

 and bears at the tip a round socket through which the stylets pass (PL 

 16, figs. 3 and 3, a). So far as I know, this condition has not been 

 pointed out before. The labrum is drawn out on the right side and 

 nears the edge of the clypeus. The clypeus is decidedly as3^mmetri- 

 cal and curves high on the left side, thus forming the, broad part of 

 the membranous connection between it and the labrum. 



Maxilla. — The maxillae (PL 16, figs, 1, g and 4) form the side walls 

 of the mouth cone. They are triangular in form, and taper strongly 

 towards their tips which fit closeh^ about the tip of the labrum. About 

 the middle of the maxillae are borne the maxillary palpi (PL 16, fig. 4, 

 b) which bear a few tactile hairs. The maxillary stylets, or lobes 

 (Pi. 16, figs. 1, i and 4, i ), are borne at the top and are jointed, being 

 composed of a short stout arm and a long tapering stylet. By low- 

 ering the angle of the short arm with the main part of the maxillae, 

 the stylets are thrust out. The segments in the maxillar}^ palpi 

 differ greatly in number and shape with different genera, even in the 

 same family. For example, in the family Aeolothripidse, members of 

 the genus Orothrips have seven segments, of the genus Erythothrips 

 • eight segments, and of the genus Aelothrips three segments. The 

 usual number in the family Thripidae is three although often only 

 two occur. In the family Phloeothripidae the usual number is two. 



