Part VII] Beeson : Life History of Toon Borer . 57 
The earliest moth emerged on the 2nd October and the latest on 
the 30th November. The period of maximum emergence occurs within 
the first four weeks of October. 
A comparison of the emergence periods of the 3rd and 4th generation 
moths (vide Tables 24, 25 and 29, 30 and Plates VIII and IX) shows 
that the two broods slightly overlap. The latest recorded emergence of 
a third brood moth is on the 29th September, arid the earliest emergence 
of a fourth brood moth is on the 2nd October. In view of the small 
number of individuals used in the experiments, it is evident that 
under field conditions overlapping normally occurs. 
5. The Fifth Generation. 
Larvae of the Fifth Generation- 
1913. W hen attention was first devoted to the life-history of 
Hypsipyla robusta in 1913, it waswfith the assumption that two or at 
most three generations occurred in the year. The preliminary work, 
while indicating that the existing accounts of the life-history of the pest 
were incorrect in this respect, was of little value as a record of the 
distribution of broods. Some of the later field data bear on the larval 
broods of the fifth generation and are therefore recorded. 
Field-work .—On the 20th December 1913, 34 toon shoots on young 
trees in the Sylviculturist’s Experimental Garden, Dehra Dun, were 
examined with the following results : — 
Shoots with healthy larvae =2o— 
One year old shoots, green 
. . . 12 larvae. 
„ „ „ „ dry . 
8 „ 
Two year old shoots, green 
3 „ 
„ 99 „ „ dry . 
. . . 2 „ 
Shoots with— 
Dead or diseased larvae .... 
7 „ 
Pupae, 1 living, 1 empty .... 
2 pupae. 
No insects ...... 
Insectary work .—About 70 shoots containing larvae (collected October- 
December 1913) were kept under various conditions in the Insectary. 
It was found that unless special precautions were taken, the cut shoots 
desiccated sufficiently to cause the death of the hibernating larva inside. 
The majority of larvae died at the end of December and early January, 
a few only survived until the 3rd week in January. The shoots kept 
under moist conditions, i.e., in tubes or porous pots, gave .successful 
results and moths were obtained in March 1914. 
1914.- —Field work. The general stage of the fifth broodlarvae in 
the field was determined by collections at intervals in February, March 
and April of infested shoots from selected localities in the Sylvicultu¬ 
rist’s Experimental Garden. 
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