!' ViyrftMiltnn 1 BUREAU OP 1 N rOMOl OOY) I 1 1 HOWARD . NUN ON I III llll I l.'l.'l M I o| llll Nol.'lll \l|| IMI \> IKU.U Tl< k ON sin 1 p, By W. I>. Hi si. /, Chargt of Cotton Boll Weei'il Inrentigatiot There are no published records of the finding of specimens of the North American fever tick [Hoophilus annulatus Say) mm iheep. In enerally been supposed that this species dot - nol occur on Bheep, although Mr. B. II. Ransom has surmised that Buch might In- tin- case. 1 In connection with the tick work <>f the Bureau of Entomol- m agent, Mr. J. I>. Mitchell, has recently obtained data which indicate a rather general occurrence of the fever tick on sheep. On account of the considerable practical importance of this matter it is thought advisable to publish this preliminary note. The practical importance of the discovery made by Mr. Mitchell lie- in the fact that the dissemination of ticks by Bheep may play a very important part in the work ol eradication that is now under way. In the general work of the eradication frequenl use must be made of the "starvation" plan under which the cattle arc removed from pastures for a considerable time. In many parts of the tick-infested area most of the cattle raisers have as many cattle as they can possibly carry on their holdings. To he forced to dispi use with the use of a part of the re ar.a in man; - ould force the Bale of :l portion of the cat- tle, perhaps it an unfavorable time for marketing. If. however, it were ble to allow Other kind of live stock to ^raze on pastures from which ticks are being eradicated according to the starvation plan, tile inconvenience and possible loss to the ranchmen would be consider- ably lessened. Sinc< th American fever tick has previously not been known to in! p, it has been thought that the pasture.- might be used for grazing these animals. The discoveries made by Mr. Mitchell, however, indicate that the dissemination of fever ticks by sheep is of suoh practical importance that, at hast in the parts of 1 where the matter has been inv ire would remain int indefinitely even if the sheep alone were allowed to roam over it. It is not .1 - in one part of the pasture l Cir. in of Animal Industry, (7. 8. I ber, 1906. to another, but a cast' of the breeding of the fever ticks on sheep, since in several cases fully engorged females have been found on these ani- mals, and they are now freely depositing eggs. The following are some of the particulars regarding data obtained up to this time. The matter will be followed up by the Bureau of Ento- mology, and a further report will be made at the end of the season. In April, 1907, Mr. A. P. Ward, of Jackson County, Tex., sent to Mr. J. I). Mitchell a number of specimens of Boophilns annulatus that he had taken from a sheep. In this lot there was one engorged female that deposited eggs which have hatched. Mr. Ward's attention was attracted to the matter by seeing this tick hanging in the hair of one fore leg. It was in the act of dropping to the ground for oviposition. At least a dozen other specimens were then collected on this animal. There were five or six nearly engorged adult females, together with sev- eral nymphs and larva:. The sheep upon which these ticks were found had not been sheared this season, although the wool was rather scant on the belly. Nevertheless, the ticks had made their way well up into the thick wool on the sides of the animal. Mr. Ward notes that the sheep was " as oily as she could be." The animal was one which had been left in an isolated field for a month before the ticks were discov- ered. In moving the herd this one had accidentally been left behind. She was exceedingly active, and there were no indications whatever of any disease. The only fact which would tend to indicate the possibility of disease in this sheep transmitted by the ticks is that she remained in the same place after the herd was removed. It is barely possible that she was left behind on account of weakness brought about by the disease at the time the herd was removed. However, subsequent evi- dence from other flocks fails to justify the assumption that there may have been any disease in this case. Earl}' in May, 1907, Mr. J. D. Mitchell examined many sheep in the flock belonging to Mr. Ward. One adult female tick was found, together with six individuals just passing from the nymphal to the adult stage. These were on several different animals, but all located in the ears. At about the same time three sheep in a flock in Calhoun County were examined by Mr. Mitchell. Two adult female ticks about ready to drop to the ground and one molting nymph were found on these three animals. Since that time Mr. Mitchell has examined ten sheep in a large flock belonging to Col. J. C. Warden, whose ranch is in Victoria County, Tex. On two of these sheep specimens of Boophilus annulatus almost fully engorged were found. They were both located on the head, near the base of the ear. Colonel Warden states that late in the summer and fall the fever ticks cause considerable annoyance on his sheep. It is necessary to treat them continuous!}' to prevent damage from screw- (forms, which are attracted by the wound lefl when the tick detachee itself or by the blood released when one happens to be crushed on the bosl . It will be noted thai fully engorged specimens of the fever tick have ii>u been found on Bheep by Mr. Mitchell in three different Mocks in as many counties in southern Texas. It is expected that future observa- tions will show a rather general occurrence on sheep There are several points of importance to be determined, as, for instance, whether the offspring of the ticks which have developed on Bheep transmit splenetic fever when placed on nonimmune cattle, and whether the sheep become diseased through the agency of the ticks. It is expected that the Bureau of Animal Industry will undertake investi- gations in the near future bearing on these points. The purpose of this circular is merely to call attention t iii. i- of inn liate practical importance. li may possibly be important to note that there are Borne peculiar features of the cattle-tick problem in southern Texas this season. Various conditions have caused unusually large numbers of ticks to be present in the Bpring. According to the testimony of cattlemen the ticks have never been more abundant in the Bpring than they are this n. It is barely possible thai this exc< Bsive abundance may have had something to do with the occurrence of tick- on Bheep, and thai under ditTerent conditions the Bheep would not have become infested. Nevertheless, it must be remembered that in that portion of T< \ well as elsewhere the cattle ticks are frequently as numerous in the fall of the year as they have been this Bpring. In view of the-e facts it -cms evident that it will he absolutely necessary in plans for eradication to exclude Bheep from areas in which an attempt is being made to eradi- cate the tici Approved : James Wilson, Secretary of Agriculture. Washington, D. C, Jum v>, 1907. O UNIVERSITY OF FLORIDA 3 1262 09216 4622