228 The Pea Thrips (Kakothrips robustus) 



lateral processes on the abdomen in either sex and by the following 

 other characters: 



K. robmius. I F. infonsa. 



Size larger TSS mm. Size smaller 1-3 mm. 



Colour very dark in both sexes. i Colour slightly paler in female, male 



I light. 

 3rcl and base of 4th antennal segments 3rd, 4th and base of 5th light. 



light. 

 Long ocellar spines between the Long ocellar spines between the 



posterior ocelli. posterior and anterior ocelli. 



3rd and 10th abdominal segments i 10th abdominal segment longer than 



equal in length. ' 9th. 



Habits of adult. 



Time of appearance. In the south of England the adult insects 

 usually appear from the middle to the end of May. The earliest date 

 observed in 1912 was the 28th May, in 1913 23rd May, and in 1914 the 

 16th May. Several correspondents speak of damage due to 'Thrip' 

 earlier than this but have never been able to supply me with specimens. 

 In the north of England it is later; in Sweden (Trybom) adults were 

 first noticed on the 1st July, while, on the other hand, Gaumont and 

 V^uillet (1914) found it in France at the end of March. 



The first specimens are found in the terminal clusters of unopened 

 leaves and in the just opening flowers. Specimens collected at this 

 time contain a large number, sometimes even a majority of males {e.g. 

 16. V. '14 Merton, 9 (JcJ 4$$ in flowers of Vicia faher). Later in the 

 year the proportion of males becomes smaller and they soon disappear. 

 With the exception of one dead specimen found at the beginning of 

 August (Kendal, Westmorland) I have found no males after the end 

 of June and, indeed, very few after the middle of this month. The 

 females, on the other hand, gradually increase in numbers to about the 

 middle of June (later in the north) and remain more or less common 

 till towards the end of July, and may be found on into August together 

 with full fed larvae on late sown peas. Bagnall (1908) found them in 

 Scabious flowers in Durham as late as "August and September." 



The males are more active than the females and escape more rapidly 

 from the flowers when disturbed. The females are often very sluggish 

 and do not leave the shelter of the flower unless this is pulled to pieces. 



A female was kept in captivity for over a month and then only died 

 by accident. It is probable that they live much longer than this. 



