C. B. Williams 241 



Thripidae. 



Frankliniella intonsa. See above (p. 227) for separation. Not 

 infrequent, often common in scarlet runners. 



Physothrips spp. {atrata, xndgatUsimus (pallipennis)). This genus, 

 which lacks the spine at the anterior angle of the prothorax, contains 

 many species which are only identified with difficulty. 



Thrips tabaci. Antennae 7-segmented ; colour varying from greyish- 

 yellow to brown ; male lighter ; common. I have found larvae and pupa 

 of this species on peas. 



Thrips physapus. Antennae 7-segmented ; colour brown ; not 

 uncommon. 



Thrips flava. Bright yellow ; antennae 7-segmented. This species, 

 which is sometimes common in the flowers, also lays its eggs in the 

 stamen-sheath and other parts of the flower. The larva, however, has 

 not the dark tail which is characteristic of F. rohusta. It usually 

 appears to be more common when the latter is absent, but I have never 

 found it sufficiently numerous to do any great damage. It also occurs 

 in scarlet runners and many wild flowers. 



In the United States beans are much injured by Heliothrips fas- 

 ciatus, which, however, unlike the present species, attacks chiefly the 

 leaves and also spends all its life, including the pupal stages, openly 

 on the food plant, there being several generations during the year. 

 It hibernates as an adult (Russell 1912). Damage has also been re- 

 ported caused by Heliothrips phaseoli (Hood 1912). We have three 

 species of the genus Heliothrips in England, but all are confined to green- 

 houses ; there would therefore appear to be little danger of the American 

 species establishing itself in this country. 



Kirchner (1890) mentions a species, Thrips pisi (Kubler), which 

 would appear from its name to be connected with peas. I have, how- 

 ever, been unable to find the original or any other reference to this 

 name. 



Natural Enemies. 



Fungus. There was very great mortality of hibernated larvae 

 owing to a fungus which attacked them even in very dry conditions. 

 The hyphae radiated out from the attacked larvae and any other larvae 

 close by became infected in a short time. 



Coccinellidae. I was able to feed larvae of Coccinella bipunctata in 

 captivity on larvae of the pea thrips, but in the wild state I have never 



