6 io 
Journal of Agricultural Research 
Vol. XIV, No. 13 
The average parasitism in all fruits by Opius humilis in 1915 was well 
above that of all the other parasites combined; in 1916 the total para¬ 
sitism by it was 17.2 per cent, and by the others combined was 16 per 
cent; while during 1917 the other parasites had so reduced the O. humilis 
that the total by it was only 12.7 per cent and by the others combined 
was 34.8 per cent. This reduction of the Opius is proceeding slowly, 
but the species is not expected to be entirely annihilated. The coffee 
collections in the Waianae Mountains at the head of the Waianae Valley 
during 1917 were interesting. This was the only point at which 0 . 
humilis had been established when the collections were made. In Feb¬ 
ruary it was found parasitizing 89.4 per cent of the larvae in the coffee; 
and in June 77.5 per cent were parasitized by it. 
The parasite Tetrastichus giffardianus Silvestri was more abundantly 
recovered from fruit collections in 1917 than in any preceding year since 
its liberation in the islands in 1914. It was recovered, however, only in 
material collected about Honolulu. Its ability to penetrate to the inte¬ 
rior of soft fruits broken or containing holes enables it when numerous to 
parasitize large numbers of larvae in such fruits as the mango, the orange, 
or the common guava. The total average parasitism in larvae from all 
fruits during the year was materially increased through the work of 
T. giffardianus in such fruits. 
The total parasitism by all species during 1917 was 14.3 per cent 
higher than in 1916. The average infestation of all fruits combined was, 
however, not strikingly different from that of 1916. 
As shown in Table III, the parasitism by Opius humilis is 4.5 per cent 
less than in 1916, while that of Diachasma tryoni , D, fullawayi Silvestri, 
and Tetrastichus giffardianus was 7,0 per cent, 5.2 per cent, and 6.6 
per cent greater, respectively. 
