382 
Annual Report for 1913 of the Zoologist. 
Recent investigations have settled some of the points which 
remained doubtful in the life-history of the pea-thrips, and 
indicated the proper treatment for it. 
The Pea-Thrips. 
This' troublesome garden pest, from which hardly any 
garden is entirely free, and which in certain years does very 
extensive injury, failed for a long time to attract the attention 
it deserved, and was annually passed over in silence in reports 
on economic entomology. In 1908 I began a serious attempt 
to elucidate its life^history, and the results were published in 
my annual report for that year. Some further observations 
were made by my pupil, Mr. Maulik, and quite recently 
another old Cambridge student, Mr. C. B. Williams, now at 
John Innes Horticultural, Institute, has been able to furnish 
evidence upon the only point which still remained obscure. 
There is little doubt, therefore, that we now have an accurate 
Fig. 1 — A young diseased pod, enlarged. 
knowledge of the whole life-history of the insect, and as 
previous accounts have been fragmentary, it is clearly desirable 
to sum up the various observations in one brief statement. 
The disease is first noticeable by the unhealthy appearance 
of the young pods. Ipstead of being uniformly green, they 
present white or straw-coloured blotches, chiefly near the ends, 
and. they usually become distorted and curled. In bad attacks 
their appearance is entirely spoiled and their yield greatly 
diminished. 
On close examination the young pods are seen to be infested 
by numbers of small yellow insects of the shape shown in Fig. 2, 
tipped with black at the posterior end. These are the young 
or larpce of the pea-thrips, which is itself black and furnished 
with four very narrow wings fringed with hairs. 
The initial stages of the attack were fully investigated in 
1908 and described in the report of the Zoologist for that year. 
The female thrips visits the newly-opened pea flowers and lays 
its eggs in the tissues of the flower, generally choosing the 
stamen sheath, but sometimes utilising the petals as Maulik has 
