Ill 
and periodic occurrence of parasites, only one species was recovered, 
Antrocejphalus destructor, at the rate of *05 per cent. The highest degree 
of infestation by Ehyssa occurred in 1920, viz., 8 per cent, in the fiftn 
generation. The numbers of the borer appear to be controlled far 
more appreciably by difierences in the climatic conditions, partly by 
the direct effect of the summer heat and the monsoon rains on the 
insect, and partly by the indirect effect on its food-supply, due to 
variation in the periods of flowering and leaf-flush. 
Platypodid^. 
For the last 10 years Platypodidae have been bred in the Dehra Dun 
Insectary from hundreds of species of forest trees, but the experiments 
have very rarely yielded hymenopterous parasites. The natural enemies 
of the Platypodidae are chiefly predaceous beetles, e.g. Histerida;, Coly 
diida;, Cuciijidse. The records obtained for Diapus jurtivus and 
Platypus uncinattis include only tliree cases of parasitism by Chalcidoidea, 
species of the new genus Monacon. It is difficult to understand how 
infection occurs, for conditions inside the gallery-system of a shot-hole 
borer are not favourable for the development of internal parasites, 
until the male beetle guarding the entrance hole has been removed, and 
the activity of the larvae has been succeeded by pnpal quiescence.* The 
parasite presumably enters the galleries of the shot-hole borer and ovi- 
posits direct in the host larva or pupa. 
Sapwood and heartwood borers. 
The genus Trigonura is parasitic on wood-borers, while the larvae are 
working in the bark and sapwood. Species including ruficaudis and 
tenuicaudis have been bred out from Heritiera Pomes in company with 
Chrysobothris, Diorthus simplex, Derolus diseicollis, Gelonceiha hirta, 
Ozotomerus mac^dosus,?^ml Glenea', ivomShorea robusta Chrysobothris, 
Xylothrips flavipes, Ozotomerus macidosus, Chlorophorus and Euryphagus 
lundi ; from Pterocarpus marsupium with Bvprestidce and Sinoxylon 
crassum dekkanense ; from Amoora rohituka with Chrysobothris, Epania 
and Coptops lichenea. The species of Chrysobothris is a not uncommon 
and widely-spread sapwood borer, but up to the present no pure in- 
fection of this insect has been obtained. 
* Vide Beeson, C. F. C., Indian Forest Records, vi, 1, 1917. The Life-History of 
Diapu furtivus Sampson. 
