416 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
A case in point is just now under consideration. It is proposed 
to bring to Bermuda from Hawaii the parasites of the Mediterranean 
fruit fly. Shall the four species now working in Hawaii all be sent 
to Bermuda, or shall only one—O pius humilis—hbe sent? In the work 
of Pemberton and Willard referred to, the conclusion was reached 
that the four parasites working together do not destroy as many 
fruit-fly larve as the Opius working alone. The Opius larva is 
destroyed by two of the others when working in the same fruit, while 
alone it is more prolific than the others. But the Hawaiian ento- 
mologists do not agree perfectly. Some believe one way, while 
others think that the more species of parasites introduced the nearer 
we come to actual control, thus backing up the stand made by Sil- 
vestri in his long controversy with Berlese. Mr. Willard, I believe, 
is of the opinion that the Opius should be sent on first and tried out. 
Among the many things that persons in charge of such operations 
must remember is the normal food of the adults of the parasitic 
forms. We have during the past few years been learning more and 
more of the habits of adult parasitic Hymenoptera of feeding by 
suction at the holes made by the ovipositor in the body of the host 
insect. It seems, in fact, to be a widespread habit and in itself is 
probably responsible for a considerable mortality among the hosts. 
But with the Scoliid wasps, whose work against underground Scara- 
baeid and Cetoniid larvae seems so important, we must study the 
botanical food of the adults—the flowers they visit by preference— 
and we must be sure of the abundance of at least closely allied plants 
in the countries into which these parasites are introduced. This also 
holds, although perhaps it is not so important, with the Tachinids 
and the Dexiids. Is it not‘a prerequisite with some of these that 
they visit the flowers of umbelliferous or other plants before pairing 
or before oviposition ? 
The expense at the receiving end must not be stinted, and the 
most expert ingenuity and care must be exercised. In many cases, 
where the parasitic supply has come from some foreign country 
without cost, all necesary expenditures must be made by the receiv- 
ing entomologists. In no case will it suffice to turn the imported 
material loose, even under the most apparently favorable conditions. 
The original supply must be multiplied by breeding, and experi- 
mental loosings must be made. 
Again and again valuable importations have been lost through 
carelessness, lack of forethought. One very promising experimental 
sending was lost to an European country, for example, for the 
reason that the man in charge went away on vacation, leaving the 
work in untrained hands. And on another occasion an expert went 
half way around the world, and after infinite care and trouble 
brought back to his home country a good supply of healthy, liy- 
