The next morning, having travelled about seven miles, they halted for breakfast; and having fettered their horse, dismissed him to feed; but when sought for the purpose of continuing their journey, he could not be found. Two travellers at length arrived, and informed them that the horse had been seen at about six miles' distance, on the way towards St. Charles: a horse was therefore hired, and a person returned in pursuit; but he was not to be found, having proceeded on his journey previously to the arrival of the messenger. The prairie flies (a species of tabanus,) are exceedingly troublesome to horses and cattle, insomuch that people who cross these grassy plains usually travel very early in the morning, and again at evening, resting greater part of the day; some, indeed, journey only by night. If they travel at all in the day, they have the precaution to defend the horse, by a covering thrown loosely over him. The tabani appear about the 10th of June, and are seen in immense numbers, until about the 10th of August, when they disappear. Near the farm houses we observed, that cattle, when attacked by them, ran violently among the bushes, to rid themselves of their persecutors.--Mosquitoes were not numerous. As they were fearful of being unable to overtake the steam-boat on the Missouri, if they made a longer delay to prosecute the search for their horse, it was determined to abandon him altogether, rather than return to St. Charles, whither he had doubtless gone; accordingly, on the 29th of June, they made a division of their baggage, and each one shouldering his respective portion, proceeded towards the margin of Loutre Prairie. When they arrived here, they determined {69} to take the most direct route towards the Missouri, as it seemed folly for them to attempt, in the drought and heat, which then prevailed, to cross the extensive plains of Loutre and the Grand Prairie with their heavy burthens. They therefore followed a path leading nearly south, along a naked ridge; where they travelled twelve miles, without finding water, and arrived at Loutre Island in the evening. They were all the day tormented with excessive thirst; and being unaccustomed to travelling on foot, they were much fatigued, and several became lame. The soil of the extensive prairies which they passed was not very good; but mixed at the surface with so much vegetable matter, accumulated by the successive growth and decomposition of the yearly products, as to give it the aspect of fertility.[100] On the south side of Loutre Prairie a well has been sunk sixty-five feet, without obtaining water; on the north water is readily found, by digging to a moderate depth. Loutre Prairie is twenty-three, and Grand Prairie is twenty-five miles in length: on the borders of each are some scattering settlements.