1 Dec., 1897.] QUEENSLAND AGRICULTURAL JOURNAL. : 469 
inquired what becomes of the parasites themselves when their source of sustenance is 
almost annihilated as a result of their own multiplication? To this question it may 
be replied that just as— : 
7 Big fleas have little fleas, 
And little, less to bite ’em ; 
And these fleas have other fleas, 
‘And so, ad infinitum— 
so also of the insects that have been considered : these in turn, have their own parasites, 
and the latter in turn parasites also. In the “Study of Parasitism” already quoted, 
the twenty-one parasites of the White Marked ‘ussock Moth had no less than 
twenty-five different insects feeding on them, and these twenty-five, no less than ten 
tertiary parasites living at their expense. 
Similarly, some of the predaceous insects feed upon the friendly ones; thus 
various pollenising insects are devoured by the flower-haunting beetles known as 
Cleride. Similarly, the Robber Flies (Asilide) carry off bees amongst other insects. 
In these two cases, there are instances of predaceous and parasitic insects coming 
within the category of what were regarded as Insect Foes from the fruitgrower’s 
point of view. 
In conclusion, it will be profitable to consider in what degree a knowledge of the 
facts relating to Insect Foes and Insect Parasitism generally, is of value to the fruit- 
grower, and to what extent he may expect to profit by discoveries relating thereto. 
Having learnt, then, that so many insects are beneficial, he might encourage them in 
two diiferent ways :—l1st. By giving them opportunities for multiplying, and generally 
protecting them. 2nd. By introducing special parasites or predaceous insects from 
countries or regions in which they exist to others in which they are absent. At the 
outset, however, it is profitable to reflect that, as a necessary result in the economy 
of nature, though there may be fluctuations in the relations between the plant-feeder 
and the predaceous and parasitic species of its own class for any given year, yet, 
when taking cne year with another, these relations remain the same, man’s eftort 
availing but little to change the conditions of life to which these different, classes of 
insects are subject; and that the exceptions to this rule, locally brought about as the 
result of man’s work, are very few indeed. 
From what has already, in this address, been stated regarding the fecundity of 
insects, it will be readily understood how, even after the approximate annihilation of 
any particular species of insect pest, their powers of multiplication being such as they 
are, the balance between Insect Friends and Insect Foes will be regained with 
marvellous rapidity : even when efforts are made to co-operate with the latter by 
assisting in the destruction of the Insect Foes that they also destroy, for these efforts 
are as a rule when successful only temporarily so and but locally applied. — 
With regard to the first measure necessary for the encouragement of Insect 
Foes—viz., their protection and multiplication—it will be necessary for the fruit- 
grower to be able to recognise Insect Friends, and to distinguish them from Insect Foes 
as well as from insects whose actions as regards his interests are neutral. At the 
outset, however, he will be confronted with a difficulty arising from the fact that, as 
arule, the most useful insects are minute creatures scarcely discernible. It has 
been stated by a very high authority in these matters—the late C. V. Riley—that “for 
the most part the nicer discriminations as to the beneficial species, some of which are 
microscopically. small, must be lelt to the trained entomologist’ (though perhaps but 
one ina thousand of these is able to distinguish between the primary parasites of 
small insects and their enemies or hyperparasites—H.T.) 
The effort of the frnitgrower willagain be further circumscribed by the fact that 
the majority of friendly imsecets work unseen, and are only known by what they 
accomplish. Notwithstanding, he may acquire a knowledge of the means of dis- 
criminating some of the larger, especially amongst the predaceous kinds, with little 
difficulty, and that this knowledge may be of service to him will appear from the 
following instances :— ; —. 
1. More than one species of Queensland Wasp collects, and ultimately destroys 
caterpillars, and will even, with eagerness to obtain its prey, tear through with its 
jaws, the tissue of leaf-mining kinds, the most difficult of all to contend with. Books 
relating to British insects inform us that the Wasp is a great fruit-eater. Without 
observation, the fruitgrower, being familiar with the latter circumstance, would 
condemn the Queensland Polistes equally with the European Vexpa, and destroy its 
nest whenever met with, And this is actually what happens in many cases. “he 
following two cases—one relating to the predaceous beetle, Cryptotemus montrouzieri ; 
_and the other, to the predaceous moth, Thalpocares coceiphaga—may also be cited in this 
connection, (Vid. Report, pp. 16 and 17.) 
