THE AMERICAN ENTOMOLOGIST. 



107 



Owing to (he severe drouth of 1868, which 

 was unfavorable to its successful transforma- 

 tions, that dreaded foe of the fruit-grower, the 

 Plum Curculio, was scarce in the early part of 

 the season, and our plum and peach trees set a 

 fuller crop Ihan they had done before for 

 years; but the subsequent moist weather was 

 favorable to tlio underground evolutions of this 

 little pest, and the new brood appeared in great 

 numbers about the end of June and beginning 

 of July, when (hey did much damage to stone- 

 fruit and some damage to pip-fruit by the goug- 

 ings which they made for food. As stated in 

 an essay read before the State meeting of our 

 Illinois horticultural friends, I have discovered 

 a little cannibal in the shape of a minute yellow 

 species of Thrips, which destroys vast numbers 

 of the little turk's eggs; and let us hope, that 

 by attacking the Curculio in its most vulnerable 

 point, this Thrips may in the course of a few 

 years reduce the numbers of the Curculio, as the 

 ladybirds have done with the Colorado Potato- 

 bug, or as the minute mite {Acarus mall) is 

 known to have done with the common Oyster- 

 shell Bark-louse of the Apple. The eggs of the 

 Apple-tree Plant-louse {Aphis mali) which last 

 winter so thickly covered the twigs of the apple 

 trees in many orchards, hatched and produced 

 a prodigious number of lice as soon as the buds 

 commenced to burst. In this immediate neigh- 

 borhood they were soon swept away, however, 

 by their cannibal insect foes, and by insectivo- 

 rous birds, such as the warblers, etc. ; but a 

 physiological fact connected with this insect 

 has been developed this year by Dr. E. S. Hull, 

 the able Illinois State Horticulturist, which is 

 of such importance that I cannot pass it over 

 even in this brief report. He has ascertained 

 thatwesutter from the injurious punctures of 

 their little beaks long after the lice themselves 

 have disappeared. In fact, he lias proved to 

 his own satisfaction that the so-called "scab"' 

 in apples, which prevailed to such au alarming 

 extent last year, and rendered thousands and 

 thousands of bushels valueless for market pur- 

 poses, is actually caused by the punctures of 

 these lice. I said that the doctor had proved 

 this matter "to his own satisfaction," because I 

 believe that caution requires that we should not 

 consider it as an established fact until all objec- 

 tions to it can be dispelled. Personally I have 

 made no observations on this matter, but the 

 facts in the case all add weight to Dr. Hull's 

 theory, if such it can be called. Hitherto the 

 cause of the "scab" on apples has been in- 

 volved in mystery. It was supposed to have a 

 fungoid origin ; yet an examination will show 



that the scabby appearance is not caused bj^any 

 live fungus, but by arrested growth of the cells 

 which have become corky and cicatrized. The 

 importance of this discovery of Dr. Hull's, 

 should it once be firmly established, cannotwell 

 be estimated; for when we have once ascer- 

 tained the cause of a disease, it need scarcely 

 exist any longer. By destroying the lice we 

 shall prevent scabby apples, and experience 

 teaches that they can be destroyed by a good 

 syringing of tobacco water. We may expect, 

 in this immediate vicinity, au almost tot.il ex- 

 emption from " scab" next year, for the apple 

 trees are remarkably free from the minute 

 black bead-like eggs of the Plant-louse with 

 which they were so thoroughly peppered a year 

 ago. 



The Tent Caterpillar {Clisincampa Atneri- 

 canci) was more abundant than usual in our 

 orchards, and the Tent Caterpillar of the Forest 

 (Clisiocampa sylvatica) also appeared in great 

 numbers both on our orchard and forest trees. 



A worm which I have called the Pickle Worm, 

 {Phricelhirn tntidali.t, Cram.), and which had 

 never been publicly noticed before, appeared in 

 immense numbers, and did great damage to our 

 cucumbers and melons by boring into the fruit, 

 but as this insect, with others, will be fully 

 treated of in my forthcoming Report, I will pass 

 on to a more general subject. 



' ■ The peblile in the streamlet scant, 



May turn the course of man j- a river; 

 Tile dew-drop on the infant plant, 

 May warp the giant oalc forever. ' ' 



In no department of science does the old pro- 

 verb " prevention is better tffan cure," apply 

 with such force as in that of Economic Entomol- 

 ogy. In my studies and observations I have 

 often been struck with the fact that many of our 

 very worst insect enemies have been introduced 

 from abroad, and that if this subject of Econo- 

 mic Entomology had been better understood 

 and appreciated fifty years ago, and the proper 

 measures had been taken to prevent the in- 

 troduction of these pests, we should at pres- 

 ent be free from the curse of the great 

 majority of them. We have, indeed, plenty of 

 native American insects, which have become 

 great pests to the cultivator of the soil, on ac- 

 count of the artificial state of things which he 

 induces. In a state of nature, a given species 

 of plant, in its struggle for existence, is scat- 

 tered promiscnously over a certain extent of 

 country, and the particular insect or insects 

 which feed upon that plant, have to search for 

 it over a comparatively extensive surface, and 

 their multiplication is con.sequently restricted. 

 But the pursuit of horticulture, for instance— 



