ENTOMOLOGICAL SOCIETY OF ONTARIO. 59 



fast in one place and a supper in another; medicine for one sick mortal and medical attention 

 for another ; and go on in this vvay for years without being known outside of his own city, 

 especially if he does not choose to advertise his generosity. But let him once fall into 

 the clutches of a dissolute woman whom he may have, out of pity, befriended, and he will 

 be publicly introduced from one side of the continent to the other, and the student of 

 human nature will, indeed, have to be exceedingly guarded in his conclusions if he 

 expects to get an unbiased estimate of this man's character, based only on the facts thus 

 placed in his possession. Yet it seems to me that he is in as proper position to do so, 

 as is even the working entomologist to pass upon the value of parasites in overcoming an 

 invasion before more or less financial loss has accrued, basing his judgment upon the fail- 

 ures to do so that have come under his observation, and necessarily leaving what he does 

 not see out of consideration. I do not believe anyone, be he ever so good an observer, 

 can, within the space of one life time, collect data sufficient upon which to base the state- 

 ment that ■' they usually appear in force only after the damage is done." Twenty years 

 of close observation of insects, in the tields, leads me to make this statement ; and I ven- 

 ture to say that in ninety-nine cases out of one hundred, an invasion of an injurious 

 insect will attract the attention of an ordinary entomologist only when its parasites tail 

 to overcome it before it has caused monetary loss. If the entomologist does not see 

 them, how much more likely is the ordinary farmer to note these conflicts between para- 

 sites and hosts 1 It is the failures that usually first attract our attention, while the suc- 

 cesses are more often unobserved, and, such being the case, how can we, with justice, 

 weigh evidence we do not possess, and of the magnitude of which we can have little con- 

 ception. 



Now, I will give a few personal observations relative to this matter, which illustrate 

 the fact that thousands of similar cases might pass unnoticed, even by those possessing 

 fair abilities for seeing such things. 



Ten years ago, in Indiana, I was studying wheat insects, and found the Wheat Midge 

 larvfe, Diplosis tritici, exceedingly abundant in a number of fields ; enough so to threaten 

 serious injury to the cro(). Soon after I observed these, considerable numbers of Coc 

 cinellidce and Telephoridm were running about over the heads of the wheat, thrusting 

 their own heads down among the bracts, and feeding among the maggots of the Diplosis. 

 Some of the TelephoridcE were venturesome enough to thrust their heads among the bracts 

 in order to secure such of their prey as were exposed by the bending of the head as it 

 swayed in the wind and were caught by the wheat head suddenly returning to an upright 

 position, and if a breeze did not soon release them, paid the penalty of their temerity with 

 their lives. Thousand of these carnivorous beetles were present, and they must have 

 destroyed millions of the Diplosis larv?e, in the ten days to two weeks they were observed at 

 work, and no peraeivable injury resulted from the invasion of the midge. 



A few years later a couple of coniferous trees on the campus of a western University 

 were attacked by a scale insect, Mytilasjns pini/olice, if I recollect correctly^ and by mid- 

 summer the leaves had a decidedly whitish tinge, as if sprayed with a dilute whitewash, 

 and besides, took on a sickly look. In the meantime a colony of Chilocorus hivulnerus, 

 or Twice Stabbed Lady Beetles, (Fig. 41), as they are commonly called, took up their 

 abode on the trees, deposited their eggs and with the larvte from these (Fig. 42) began to 

 destroy the scales. All through the autumn the contest was waged, and with the coming 

 of cold weather all the beetles, which had long before escaped from their pupa caass, went 

 into winter quarters. With the coming of spring they were observed to return to the trees, 

 and again began the contest in turn giving way to their larvae, and these emerging as adults. 

 In early summer the ends of the branches began to show leaves free from scales, and by 

 the coming of winter again the outbreak of the pest had apparently been entirely overcome, 

 and the fall rains washed olFall vestige of the conquered hosts. The invasion had been over- 

 come, and I doubt if another person besides myself had been aware of the two years' conflict. 



Later, the maples along one of the principal residence avenues of Columbus, Ohio, 

 were threatened with an invasion of the Maple Bark Louse, Pulvinaria innumerahilis, 

 (Fig. 43), and the trees would certainly have been overrun the following year, had not 

 this same Lady Beetle appeared in numbers, and with their larvte so reduced the pest in 

 numbers as to render injury impossible. 



