July 7, 1923 
Mediterrcmean Fruit Fly in Hawaii 
3 
secured during almost every month of the year. Consequently, Indian 
almond has been used more than any other fruit in securing parasitism 
records of the fruit fly. Average infestation records of this fruit alone, 
of which about 30,000 are collected yearly, are a good guide to the abund¬ 
ance of C. capitata in this locality. In 1919 and 1920 this average 
decreased 15 per cent and 44 per cent, respectively, over that of 1918. 
These are the first important decreases in infestation of preferred host 
fruits that have taken place since parasitism records were started. 
Table II, which records the parasitism of the larvae in each host fruit 
by the month, reveals interesting information relative to Diachasma fulla- 
wayi and Tetrastichus giffardianus. Prior to 1920 the former had a 
tendency to attack its host freely in only a few fruits, namely, straw¬ 
berry guava (Psidium cattleianum) , coffee ( Coffea arabica ), French 
cherry {Eugenia uniflora) , and yellow oleander ( Thevetia neriifolia ). 
Other fruits occasionally yielded larvae that were parasitized by D. 
fullawayi; but the 1920 records show larvae, in nearly all fruits under 
observation, to be freely attacked, especially during the latter part of 
the year. It caused the death of 12.1 per cent of all larvae during the 
year (Table IV), which is more than double its percentage of parasitism 
during any of the previous five years, with the exception of 1917, when 
it was 7.3. T. giffar dianus has also shown an increase over previous 
years, although not so great an increase as D. fullawayi . It has proved 
its value by its ability to attack its host in fleshy fruits, where the fruit- 
fly maggots are protected to a considerable extent from the opiine para¬ 
sites. T. giffardianus attacks its prey within the fruit, after entering 
through a crack or other opening, by attaching itself to the larva while 
ovipositing. In this manner it can reach many larvae which are out of 
reach of the opiine parasites, which oviposit only in larvae near the 
surface, by piercing the skin and pulp of the fruit with their ovipositors. 
If fruits with thin skin and shallow pulp, like the Indian almond and 
coffee, were the only ones grown in Hawaii, the opiine parasites now 
there would probably control the fruit fly; but the fleshy fruits, such as 
the guava ( P . guajava ), of which there are thousands of acres and in 
which these parasites work with difficulty, serve as a constant source of 
supply of adult fruit flies. It is interesting to note that T. giffardianus 
attacked the larvae in guava very freely during 1920. In six out of the 
nine months during which records were obtained it destroyed more 
larvae in this fruit than the other three parasites combined. The records 
for 1919 and 1920 have greatly enhanced the value of this parasite. 
