November 15, 1889.} 



SCIENCE. 



535 



teachers of science and employers of such teachers will use the 

 ■columns of this weekly to make public their needs, that they may 

 be the better filled. We appreciate that the commercial spirit is 

 weak in the class to which we are appealing, but it is hard to be- 

 lieve that it is so weak as not to lead them to write us a postal the 

 ■contents of which when published may lead to an improvement in 

 their position. 



Col. M. H. Crump of Bowling Green, Ky., is carrying on ex- 

 periments to see whether the air from the so-called Grand Avenue 

 Cave cannot be used for regulating the temperature of a proposed 

 hotel at that point. We have already called attention to these ex- 

 periments, and Col. Crump has advertised in Science constantly 

 for some weeks for information on the use of cave air for such 

 purposes, but none of the readers of Science have much to offer. 

 The scheme is novel, and the prominent geologists of the country 

 ■who have been consulted have expressed considerable interest in 

 the outcome. 



THE HORN-FLY. 



The knowledge of this pest now in the possession of the division 

 of entomology of the United States Agricultural Department is 

 sufficiently far advanced to enable it to present a preliminary 

 article in the last number of Insect Life, giving the mam facts 

 ■ascertained. A more complete article will be published in the 

 annual report. 



Attention was first called to this pest in September, 1887, when 

 ^Mr. I. W. Nicholson of Camden, N.J., wrote to the department, 

 under date of Sept. 22, as follows : " Herewith I send some speci- 

 mens of flies which appear to have made their first appearance 

 about the middle of August. They are very annoying to cattle, 

 but rarely settle upon the horses or mules. They gather in patches 

 ■or clusters, particularly upon the legs, and are very active. I 

 should like to know if they are common in other parts of the United 

 States. They appear to be very numerous in all the counties near 

 Philadelphia, yet I have seen no person who has observed them 

 before this season." 



Later letters the same season from Mr. Nicholson mentioned 

 the common habit of clustering upon the horns, and the fact 

 that after a severe frost in the middle of October the fly disap- 

 peared. 



May 15, 1888, the same gentleman wrote that the flies had 

 promptly made their appearance May 10, or a little before, in great 

 numbers. A few days later the same insect was heard of in Har- 

 ford County, Md., through Mr. George R. Stephenson, who re- 

 ported its occurrence in that locality the previous summer. 



By the summer of 1889 the pest had extended in numbers much 

 farther to the southward, and the department was early informed 

 of its occurrence in Harford and Howard Counties, Md., and Prince 

 William, Fauquier, Stafford, Culpeper, Louisa, Augusta, Bucking- 

 ham, and Bedford Counties, V'a. The alarm became great. Con- 

 siderable time has therefore been devoted to the study of the habits 

 and life-history of the insect. This was done mainly by Mr. 

 Howard, who made a number of short trips to The Plains, War- 

 renton, and Calverton during June and July. Later in the season 

 Mr. Marlatt assisted in the work, which had been greatly facilitated 

 by Mr. G. M. Baslable, Mr. David Whittaker, Mr. M. M. Green, 

 and Mr. William Johnson, and particularly by Col. Robert Beverly. 

 Aug. 20, Mr. Howard found the flies practically in Washington, — 

 in Georgetown, — and the next day Mr. Marlatt found them in 

 Rosslyn, at the Virginia end of the Aqueduct Bridge, so that 

 further trips for material were not necessary. 



The result of the summer's observations by these two gentlemen 

 is that the life-history of the insect has been accurately made out 

 from the egg to the fly through several consecutive generations, 

 and that substances can be recommended which, from their ex- 

 perience, will keep the flies away for from five to six days ; while 

 from the life-history a suggestion as to preventives is made, which, 

 under certain circumstances, will prove undoubtedly of great 

 benefit. 



Since this insect was first brought to notice, it has been felt that 

 it was an imported pest. Its first appearance in the neighborhood 

 of Philadelphia, and its gradual spread southward, have favored 

 this idea. The fact that in this country it has spread with much 

 greater rapidity towards the south than towards the north would 

 seem to indicate that it is a south European species. 



The exact time and place of the introduction, it is impossible to 

 ascertain. Upon its first importation in small numbers, it was 

 probably for some time unnoticed, and its first noticeable appear- 

 ance may not have been at the point of importation. 



All imported cattle from Europe pass through the quarantine 

 stations of the Agricultural Department at either Littleton, Mass., 

 Garfield, N.J., or Patapsco, Md,, and an examination of the records 

 develops one or two points of interest. Since 1884 only ten head 

 of cattle have been imported into the country direct from France. 

 All of these have passed through the New Jersey station, but their 

 ultimate destinations have in no cases been within the regions now 

 infested with the fly. The other importations have been from 

 points like Antwerp, London, Amsterdam, Hamburg, Glasgow, 

 Liverpool, Southampton, Hull, Rotterdam, and Bristol. The year 

 1886, immediately preceding the appearance of the fly, was 

 marked by quite an extensive importation of Holsteins from Am- 

 sterdam and Rotterdam and London, through the Garfield station, 

 mainly for parties in New York City. Over three hundred were 

 imported, and an interesting point to investigate will therefore be 

 the occurrence or non-occurrence of this fly in Holland. 



The popular name which is here adopted — the " horn-fly " — 

 has the sanction of popular use. It is sufficiently distinctive. The 

 names of " Texas fly " and " Buffalo fly " and " Buffalo gnat " are 

 also in use in some sections, and indicate an impression that the 

 insect came from the West. Dr. Lintner uses the term " cow-horn 



fly-" 



The most prominent of the popular errors is the belief that the 

 fly damages the horn, eats into its substance, causes it to rot, and 

 even lays eggs in it,' which hatch into maggots and may penetrate to 

 the brain. There is no foundation for these beliefs. As will be 

 shown later, the flies congregate on the bases of the horns only to 

 rest where they are not liable to be disturbed. While they are 

 there, they are always found in the characteristic resting position. 

 Where they have been clustering thickly on the horns, the latter 

 become fly-specked, and appear at a little distance as though they 

 might be damaged ; and it is doubtless this fact which has given 

 rise to the erroneous opinions cited. 



Mr. Howard's first impression upon entering the field, that the 

 eggs would be found to be laid in freshly dropped dung, proved to 

 be correct. He brought to Washington with him from Calverton 

 dung dropped on the night of July 28, and exposed in the field 

 during the 29th ; and from this dung the first adult flies, five in 

 number, issued Aug. 7, only ten days from the laying of the eggs. 

 This settled the point of place of oviposition and breeding. It 

 seemed probable that this was the only substance in which the 

 species breeds, as indeed it is the only likely substance which exists 

 in sufficient quantity through the pastures to harbor the multitudes 

 of flies which are constantly issuing through the summer. How- 

 ever, many living females were captured, and placed in breeding- 

 cages with horse-dung and decaying animal and vegetable material 

 of different kinds, each isolated ; and it resulted that a few ovipos- 

 ited in the horse-dung, and four flies were reared from this sub- 

 stance. There is no evidence, however, that in a state of nature 

 the flies will lay their eggs in any thing but cow-dung. 



The time and manner of oviposition were puzzling at first. 

 After hours of close watching of fresh dung in pastures close to 

 grazing cattle, not a single HcBinaiobia was seen to visit the dung, 

 much less to lay an egg. This close observation was made at all 

 times of the day from dawn till dusk without result, while breeding- 

 cage experiments were all the time proving that nearly all fresh 

 droppings contained many eggs. With some hesitation, therefore, 

 the inference was made that the eggs were presumably laid at 

 night. 



The question was, however, considered by no means settled ; 

 and, on the discovery of the fly at Rosslyn, Mr. Marlatt was 

 directed to make especial observations upon this point. The first 

 result was, that careful examination of dung dropped in the early 



