ENTOMOLOGICAL SOCIETY OF ONTARIO. 87 



tember they are up with their prey, but then it is too late ; the crop has been destroyed, 

 and although it is quite probable that the late broods have entirely rid the vines of plant 

 lice, yet it has not benefitted the farmer one solitary cent. I had a beautiful opportunity 

 of observing this in 1892. It was a pleasure to see how the late broods moved from vine 

 to vine, leaving scarcely a living louse behind them ; but that .same vine was dried and 

 withered ; whatever fruit there remained on it was undersized, blackened by honey-dew, 

 half ripe, and never in fit condition for market. Acre after acre I have seen in just that 

 condition, and practically no revenue has been derived from the land. It is quite true 

 that the beetles exterminated or nearly exterminated the plant lice, but this did not 

 advantage the farmer one solitary cent. A few buckets of kerosene emulsion libt rally 

 applied early in the season, while the plant lice were running away from the lady-birds, 

 would have been of a great deal more money benefit than all the aid that nature gave. 

 My contention is, that in dealing with injurious insects from the farmer's standpoint, we 

 can entirely ignore the work of parasites or predaceous insects. We must accept the fact 

 that each year these insects will appear in about the same numbers ; that nature has 

 evidently assumed that this is about the proper number to appear, and that all her checks 

 are arranged accordingly. If we wish to lessen them, we must do it by means other than 

 those which she has provided. 



There is, of course, a possibility that we may in some cases make use of either para- 

 sites or predaceous insects. That has been very well illustrated by the instance before 

 referred to, that of the Vedalia and the Icerya. The one point that is overlooked by the 

 majority of those who see only newspaper accounts is, that we had to deal in the first place 

 with an insect which was not a native, but which was imported. In the second place the 

 insect preying upon it was also imported, and found as the only familiar form upon which 

 it has been used to feed just this one species. In bringing over the Vedalia, its natural 

 checks were not brought with it, and in liberating it in the orange groves of Californiaj 

 it was given an advantage that it could never have possessed in its own country. There 

 may be a few of our insects in a somewhat similar position, and po3sibly some one of us 

 may yet be as successful as Dr. Riley was in reference to some other peroaanently injuri- 

 ous species. It may even be that parasites which in their native home are not able tu 

 control or exterminate the species upon which they prey, may when introduced into this 

 country, have such an advantage that they will accomplish more than they could in their 

 native home. I say this may be so, but I do not anticipate it in many cases. Insects 

 are very slow to change their habits. Just as it is rare for an American parasite to 

 attack an imported insect in any numbers, just so rarely will we be able to induce a 

 European or other foreign parasite to attack the American insects. We have a field here 

 which is comparatively new, and of which we know very little, but it is not that 

 particular field that it is my intention to enter. The propositions that I do make, and 

 that I am ready to defend are : Among our native insects parasites act merely as a check 

 to excessive increase. Excessive increase means more than the natural food of the insect 

 is able to support, and does not mean excessive increase in the sense of the farmer. An 

 insect that is, under natural conditions, abundant each year, must be dealt with without 

 any regard to parasites or natui-al enemies. Other than I have just suggested, parasites 

 and predaceous insects have absolutely no economic value. 



