280 



TKANSACTIONS OF THE NORTHERN 



suiToimds it, lias not yet mouldered away into its primitive elements, this sad memorial of what our 

 fate is soon sure to be, liecomes no fitting scene for such display, and on tlie present occasion witli 

 our hearts draped in mourning Ave can not make the review, but upon some more litting occasion we 

 promise to review so much as will be thought useful to the scieutiflc world, and not personally 

 applical)le to the illustrious dead; who was one of the associate authors of one rather harsh paper on 

 this subject. 



The causes of disease among insects lurking in the fluids in which they move, as well as drugs that 

 are lltting applicants to carry disease and death into their ranks, are laudable and proijer objects for 

 the study of the practical entomologist. 



Diseases.— Why should we not admit that fatal diseases visit these lower forms of life as well as the 

 various departments of the Vertebrat;e. Fishes are not exempt; birds are not immortal; even the 

 wild beast has no insurance agent. Domestic animals feel the sharp arrows of the king of terrors; 

 hogs smitten down with cholera, cattle more than decimated with pleura-pneumonia and rinder-pest, 

 horses alllicted with fcAers and tuberculosis, and man himself the subject of a thousand ills. If man 

 himself with his complex antl most perfect organization— a machine that has more of the elements of 

 self-rejjair than any other of which we have any knowledge— re(iuires the aid of some physician at 

 every turn in life, to help in producing these repairs, what maj' we say of the frail creatures of a 

 day that are possessed of a less perfect organization. If man, so well fortified, is not proof against 

 epidemic disease, what can we expect of these? 



In answer to the main question if "Half the children that are born, die before they are one year 

 old, does it follow therefore that they all die of epidemic diseases?'" We reply, is this a fact? 

 Among the liealthj' and naturally reared, how many families read a different history. And admitting 

 that it l)e true, do not most of those who have had liealtliy parents and good food and pure air that 

 thus die early die of epidemic diseases— cholera, cholera morbus, scarlatina, disenterj-, fevers, etc.? 

 And if the youths that have not yet attained maturity in all Nortliern Illinois, Iowa, AVisconsin and 

 Minnesota should so eft'ectually die off in one short summer (even in one month of it), as to depop- 

 ulate all this district for a number of generations, although the extermination should not i)rove to 

 liave been for all practical purposes so entirely complete in Southern Illinois,* Missouri and Kansas, 

 would it not look still something like an epidemic? Tlie fact being apparent that they died not of 

 fire, water, famine, or the sword ! Let us always hail with delight the discovery of every great truth. 



A few years ago, while I was brooding over the fate of our apple trees from the rapid increase of 

 the great army of bark lice, I suddenly one day saw a beacon light of hope looming up before me in 

 the form of my acariau parasite— a little stranger without a name appeared suddenly in our midst, 

 audi received it into my arms, and became its foster father; nameless and friendless, I supplied it 

 with my own, and first introduced it into public notice at your organizing meeting in our little 

 village of Mt. Carroll. When I took my seat the venerable Walsli immediately arose in confirmation 

 of my announcement. A flood of light thus burst upon you that you have and ever will hail witli 

 greater joy, as apple grov/ers, than any otlier that has ever appeared in connection with the apple 

 tree, and while the life of tlie bark louse lasts, I now predict it once for all, this little foundling will 

 be more useful as an eftectual "counter worker" of the apple bark louse than any agent or device 

 that man can contrive. How many a patent nostrum has already unconsciously stolen the credit of 

 much merit from this humble worker. 



But do not become alarmed, it is not my purpose to torment you with a lengthy disiiuisition of the 

 doings of bark-lice, after my paper on the " Bark-louse in 1868 " which you published last year, and 

 after all tliat I said on the subject a few days ago at Ottawa, and in anticipation of the Essay upon the 

 same suljject that I see bj- the programme you have, in the order for to-morrow. 



But I have one tiling to which I may l)e permitted to call your attention. A few days after I 

 returned from the annual meeting of the State Horticultural Society at Ott;iwa, I was examining tlie 

 contents of some wild bark lice-shells (lecancuni) from the woods, microscopically, and was 

 delighted to find a form of acarian parasite with six legs, in the larval state, also the perfect or eight 

 legged insect. This agreed precisely with the notes on this subject by the State Entomologist in liis 

 report, on the mites parasitic on api>le bark lice, he describes the young of those he observed as 

 liaving six legs. Subse(|uently when I visited him at Rock Island, he asked me if I had ever found 

 any siiecimeus witli six legs, and wlien I assured him that after frequent microscopic, examinations 

 of specimens of all sizes I had seen none but eight legged specimens, he remarked that as he had not 

 used a microscope but instead, a good coddiiigton lens, it was barely possible that he had not 

 ' detected one pair of legs. This discovery however confirms his )vritten history of these mites, that 

 there is a variety, with but six legs in the young state, although I erroneously had thought dill'erentl)', 

 and that those that 1 originaly discovered and described as Acarus? Mains, probably always have 

 eight legs, at least this is the appearance so far as I was iible to oliserve. If this proves to be strictly 

 persistent, in this manner, we must have two or more species of mites, and probably of different 



*Even there my "prophecy " is good, because chinch bugs have not, so far as I can learn, been as numerous as in 

 those of their palmiest days. 



