practical man who is not a naturalist introducing noxious insects or the 

 parasites of useful insects is very much greater than if the work be in the 

 hands of a trained entomologist who knows his work. The latter may not 

 introduce so many insects, but there is a very much greater possibility of 

 their being of use. Then the question arises, what are we in Australia to 

 introduce 1 We have found by experience that we can control scale insects of 

 all kinds (which are the orchardist's worst enemies), either by spraying or 

 fumigation ; and that for citrus trees there is nothing so effective and rapid, 

 when properly carried out as fumigation with hydrocyanic acid gas. 



We find many natural parasites attacking the different native and intro- 

 duced scales, both ladybirds and-internal parasites ; but, as in other parts of 

 the world, they will not give us clean fruit unless they are assisted. 



We do not need ladybird beetles, for our insect fauna is so rich in 

 Coccinellidse that they are hunted for and collected by investigators from all 

 parts of the world. In fact, as previously noted, some of the keenest advo- 

 cates, when ladybirds were the fashion, have lately turned a cold shoulder 

 on these beetles, and claim that the micro-hymenoptera or chalcid wasps are 

 very much superior. 



The American and foreign bulletins for the last twenty years have been 

 full of descriptions of new species of parasites. Interesting papers on the 

 development, and calculations based on the percentage that have been bred 

 from different scales and other pests worked out, until results have been 

 shown, upon paper, that in theory prove that each particular pest is doomed 

 to extinction ; but in practice there is always some little weak spot that has 

 not been taken into account, the pest raises its head again, and we go back 

 to the old methods. There is no question that, from a scientific point of 

 view, there is not a more interesting study in the field of economic entomology 

 than working out the life histories of these interesting little insects ; but 

 when it comes to hard facts, how many of the much-praised insect parasites 

 that have been written up have been a factor in relieving the orchardist or 

 gardener of the labour of spraying, fumigating, and other more mechanical 

 means of checking the ravages of insect pests 1 



The ideal introduced parasite is one that can be bred in a large State or a 

 private insectarium in sufficient numbers that it can be distributed just at 

 the critical time when the particular pest it destroys is in evidence, which, 

 when it is once liberated in the orchard and garden, can establish itself 

 against all comers in sufficient numbers, adapt itself to its surroundings, and, 

 when its food supply is exhausted or has reached the vanishing point (a 

 natural consequence if it is to be an effective parasite), will either find some 

 other insect to devour, or will hibernate until fresh supplies come into 

 existence. 



The discovery of such an admirable parasite has been proclaimed again 

 and again ; but it is much to be regretted that it has become the habit of 

 entomological collectors to enlarge upon the great value of their discovery 

 before the insects have reached their destination, and to proclaim, not what 

 it has done, but what it is expected to do when introduced into its new 

 home. 



The results of my investigations into the actual importance of the Spanish 

 Codling Moth Parasite (CaliephiaUes messer), in relation to its value in the 

 apple orchards of California, are recorded in the general part of this report, 

 and have since been borne out by the latest information available. This 

 large black ichneumon wasp was advertised round the world, figured and 



