PROSPECTS FOR 1887. < 1 



rain into tbe sewer traps. jSow, however vigilant the authorities may 

 be during the heat of summer in cleaning out these traps, at the ap- 

 proach of cold weather the necessity for their frequent cleaning is sup- 

 posed to be removed. As a consequence of this, vast masses of black, 

 decomposing, and reeking leaves are left to fester during the late fall 

 and early winter, and even through the whole winter, sending forth theii 

 injurious and insidious emanations from every street corner. From 

 personal experience we are convinced that this is a source of much sick- 

 ness hitherto almost entirely overlooked, and it behooves the authori- 

 ties to have the traps on all the tree-planted streets thoroughly cleaned 

 out immediately after the trees have become essentially bare. 



PROSPECTS THE COMING SEASON.— CONCLUSION. 



From the habits of the Orgyia as compared with the Web-worm there 

 is good reason to believe that the former will become in the future more 

 and more numerous and more and more of a nuisance, just as it has be- 

 come the most grievous pest in Boston and Philadelphia and other cities 

 where the trees are older. As to the prospects of a repetition of the 

 Web-worm nuisance the coming season, the probabilities are that it will 

 be very much less troublesome than it was in 1886. It is almost a uni- 

 versal rule in insect life that abnormal increase of a plant-feeding species 

 is followed by a sudden check. This is due to two causes : First, the 

 great multiplication of the parasites and natural enemies of the species 

 which such undue increase permits; secondly, to the greater feebleness 

 and tendency to disease resulting from insufficient food, which is a very 

 general accompaniment of such undue increase. From the diseased 

 condition in which the bulk of the last generation of the Web-worm 

 was found, and from the great increase in its parasites that we know to 

 have taken place from actual observation, we may safely expect ex- 

 ceptional immunity the present year, 



SOURCE OK ILLUSTRATIONS. 



Plate I is from a photograph. Figures 1, 2, 3, 1, 5, (J, and 11 are republished from 

 former Government reports by the author. Figures 7, 1% 13, 14, 15, 'JO. 21, 22. ami 26 

 are from the author's Reports on the Insects of Missouri. Figures i», 10, ami 25 are 

 from other miscellaneous papers by the author. Figure 8 is from Hubbard, ami fig- 

 ure 16 is from Glover; while figures 17, 18, ID, 2;?, 24, ami 27 wore drawn tor this Bul- 

 letin and for our Annual Report as Entomologist to the Department of Agriculture 

 for 188C. 



