20 EEPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



From what I have said above, it follows that I cannot i)redicate with the same assur- 

 ance that I have done in Texas, Missouri, Kansas, and Iowa; but, to be brief, the pros- 

 pects are, in my opinion, quite favorable. * * * 



Dr. Packard, of the Commi&sion, who has been through Utah, Idaho, Montana, and 

 Wyoming, confirms my conclusion that the Northwest must be measurably depleted, 

 for he could not find a locust in Montana from the Idaho line up to Fort Benton or 

 down the Missouri line to Bismarck. None are to be seen in the region south of South 

 Saskatchewan, and there is an immense area free from them in their native home. 

 There is very little danger, then, of injury from Fall swarms from the Northwest, unless 

 they come from the Black Hills country. There remains the chance of swarms from 

 your own western parks and plateaus or from those of Utah ; but I have good reasons 

 for believing that they will prove no more injurious than the swarms which have been 

 passing on several days since I have been in the State from said western hatching- 

 grounds. There is a constant struggle for supremacy between the plant-feeder and its 

 carnivorous enemies. The Rocky Mountain locust got the upper hand during the ex- 

 cessively dry seasons of the early part of the present decade, and has been so numer- 

 ous for the past three or four years that its enemies have rioted in plenty, and at last, 

 in their turn, have increased inordinately. In all your parks the Tachina flies (which 

 produce the parasitic maggots known to infest the locust) are so numerous as to 

 cause a constant buzzing like a swarm of bees, and to prove a positive nuisance to 

 tourists. Every winged locust that attempts to fly is pursued by three or four of them, 

 and the locusts that are daily rising from said parks, whenever the breeze is favorable, 

 are very generally parasitized and diseased in consequence. The same holds true, as 

 I learn from reports, in Utah, and as the parasites will increase as the season advances 

 there is no reason to believe that the later swarms from the west of you will prove 

 more injurious than those that have already left. The same will also largely hold true 

 of those which leave the Black Hills country, though I have less positive information 

 from that region. Nature maintains her average in the long run, and a few seasons of 

 drought and locust ravages are apt to be followed by a period of more rainy seasons 

 and locust decrease. 



REMEDIES. 



As these have been quite fully given in the Commission's bulletins, and are not par- 

 ticularly called for at this season, I will dismiss the subject with the remark that I 

 have found no means employed in Colorado that are not employed in other States, ex- 

 cept as your irrigating ditches permit of a peculiar and satisfactory use of coal-oil. I 

 should, perhaps, except also one means employed in the Wet Mountain Valley, where, 

 as the young insects pass from the ledges and benches where they hatch into the val- 

 ley, they are so effectually rolled into a slush made by overflowing the ground, that a 

 pestilence from their dead bodies is sometimes threatened. I think your farmers are 

 not sufficiently appreciative of the dry ditch, which could of len be used to great ad- 

 vantage where other means fail. 



The Commissioners consider it their duty not only to disseminate information already 

 possessed, but to gather from all parts of the country the facts peculiar to each section, 

 for experience differs immensely with latitude and surroundings. The flights of the 

 winged insects — their direction and the direction and force of the wind at the time in 

 Colorado during the rest of the season — will be of great interest, and the Cr.rauiission 

 will feel under obligations to any of your readers who will send me notes thereon. 

 Yours, very truly, 



C. V. RILEY. 

 Summit, La Veta Pass, July 28, 1877. 



' Mr. William Holly, of Del ]t^orte, as stated in the above letter, was 

 employed as special assistant in this State, traveling extensively on 

 horseback during June and July to collect information in the southern 

 counties. His report, with other data, appears elsewhere. (App. 7.) 



