236 Tlte Pea Thrips (Kakothrips robustus) 



Description. 



Colour. Head, thorax and abdomen shining orange-yellow. Antennae, legs and 

 wing cases more transparent and almost colourless. The last two abdominal seg- 

 ments are also pale and semi-transparent, not dark as in the larva. The eyes are 

 dark red-brown. 



The antennae are laid back along the top of the head and reach to about the 

 middle of the pronotum ; between them the ocelli are visible. The wing rudiments 

 reach to the seventh abdominal segment. The hind margin of the ninth abdominal 

 segment is produced into several long tooth-like processes. Two long spines near 

 each front angle of the prothorax, two near each hind angle, one near the middle of 

 each lateral margin and one pair on the hind margin. Length 1-6 mm. (measured 

 from life), broad in proportion. 



The pupa darkens slightly before the emergence of the adult, but 

 the latter is still pale and soft on escaping. It remains alongside the 

 old pupal skin gradually hardening and darkening in colour for about 

 two days, after which it works its way through the soil to the surface 

 and is ready to start a new cycle of life and destruction. 



The life-history of K. robustus as described above is very similar to 

 that of Taeniothrifs (Euthrips) pyri, the pear thrips. This latter is 

 also single brooded, has two larval stages and spends the greater part 

 of the year as a full fed larva in the earth beneath the infested trees. 

 Stenothrips graminum, a species found on cereals in this country and on 

 the continent, also hibernates as a larva deep in the ground (Kurd- 

 jumov, 1913). 



Distribution. 



British Isles. 



I have received records or specimens from twenty-nine counties in 

 England, Wales and Ireland as shown in the map (Fig. 11) and below, 

 but so far have not any record for Scotland. I have received bags of 

 peas from a few localities in that country which were all quite free, and 

 Professor Macdougall, of Edinburgh, tells me that he knows of no record 

 of damage. It is probable, however, that it occurs at least in the 

 south as I had but few correspondents, and, as has been mentioned above, 

 the species occurs on the continent as far north as Sweden. Some of 

 the records below are based on only a few s})ecimens. The districts 

 where it is numerous enough to do damage are chiefly in the south and 

 east; I have, however, one record of damage as far north as Cheshire. 

 The absence of records from counties in many cases only means that 

 I had no correspondents in that district and must not be taken to 

 imply the absence of the thrips from that district. 



