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THRIPS ORYZAE, SP. NOV., INJURIOUS TO RICE IN INDIA. 



By C. B. Williams, B.A., F.E.S. 

 (The John Innes Horticultural Institution, Merlon, Surrey.) 



Up to the present time no single species of the cosmopohtan genus Thrips has been 

 recorded from the mainland of India. In fact our knowledge of the Thysanoptera of 

 this country is extremely fragmentary. Schmutz in 1913 (Sitzb. der K. Akad. 

 Wissensch. in AVien, Math-nat. kl. cxxii, p. 1-99) described forty-four species from 

 Ceylon, and since that time about a dozen more have been added, and no doubt many 

 of these will be found to occur on the mainland. At present, however, only seven 

 species are recorded. These are : Physothrips lefroyi, Bagnall, Physothrips usitatus, 

 Bagnall, Heliothnps indicus, Bagnall, Panchaetothrips indicus, Bagnall, Hindsiana 

 apicalis, Bagnall, Phoxothrips breviceps, Bagnall, and Leeuivenia indicus, Bagnall. 

 It is probably no exaggeration to say that there are at least two thousand species in 

 that country still awaiting discovery. 



The present species Thrips oryzae is reported by Mr. E. Ballard, the Government 

 Entomologist at Madras, to be injurious to young rice. It comes in that section of 

 the genus Thrips with the head almost as long as wide, and with a more slender 

 prothorax. Many of this section have been placed at times in the genus Bagnallia, 

 but the line of separation of these forms from those with broader heads is so indistinct 

 that the erection of another genus for them only causes further difficulty. I propose 

 that, for the present at least, Bagnallia be considered as a subgenus of Thrips. 



The genus Thrips is in almost greater confusion than any other genus of this order, 

 many species having been badly described by writers without reference to known 

 species. The only course under the circumstances is to describe the species below as 

 new, and so that it can be recognised, and to wait for the time when the rediscovery 

 or rejection of certain forms makes a revision of the whole genus possible. 



Thrips (Bagnallia) oryzae, sp. nov. (fig. 1). 



Female (macropterous). 



Measurements : Head, length 0*110 mm., width 0*120 mm. ; prothorax, length 

 0-130 mm., width 0*146 mm. ; pterothorax, length (mid dorsally) 0*172 mm., wddth 

 0*208 mm. ; 9th abdominal segment, length 0*080 mm. ; 10th segment, length 

 0*052 mm. ; wing, length 0*66 mm., width 0*046 mm. ; total body length 1*04 mm. 

 Antennae, segment 12 3 4 5 6 7 



length (//) .. 21 31 36 30 29 37 19 



width (/^) .. 27 27 19 18*5 18 18 8 



Total length of antenna 0*210 mm. 



Colour. Body uniformly dark brown ; legs similar, except for the fore tibiae and 

 all tarsi, which are paler but still brown ; antennal segments 1 and 5-7 dark, 2 and 4 

 paler, 3 still paler ; o cellar pigment reddish brown. General form slender. 



Head (fig. 1, a) about one- tenth wider than long, the sides almost parallel, cheeks 

 not arched. Eyes not large, very slightly projecting, distance between the eyes about 

 one and a half times the width of the eye ; distance from the eye to the back of the 

 head about one and a quarter times the length of the eye. Ocelli forming a slightly 



