394 



THE AGRICULTURAL NEWS, 



December 



1912. 



INSECT NOTES. 



TICKS. 

 PAET I. 



An important contrilmtion to the knowledge of North 

 American ticks has been issued recently by the United States 

 Department of Agriculture as Bulletin No. 106 of the Bureau 

 of Entomology. The authors are Messrs. Hooker, Bishopp 

 and Wood, and the publication has been prepared under the 

 general direction of Mr. AV. D. Hunter. The title 'The Life 

 History and Bionomics of some North American Ticks' indicates 

 the lines on which the investigations have been carried out. 



Reference to previous articles by Mr. Hooker and 

 Messrs. Hooker and Bishopp will be found in the Ai/rtcultural 

 ^ews. Vol. X, p. 314, in the Insect Notes entitled: 'Informa- 

 tion Concerning Ticks.' 



On account of the importance of ticks generally, and of 

 the limited knowledge regarding the ticks of most of the 

 Leeward and Windward Islands, it is proposed to reprint in 

 the A'jricuUural Neii:s, two of the introductory chapters of 

 Bulletin No. 106, for the information of the planters and 

 others in these islands who are, or ought to be, interested in 

 these parasites. 



One of these chapters 'The Economic Importance of 

 Ticks' is reproduced herewith; the other 'Collecting, Preserv- 

 ing and Mounting Ticks' will appear in the next number of 

 this journal. 



'Ticks are of economic importance (1) as agents in the 

 transmission of infectious diseases, and (2) as external para- 

 sites, both of man and the lower animals. At least two 

 distinct diseases of man and eight or more of domestic animals 

 are known to be thus transmitted, at least seventeen species 

 of ticks being involved as carriers. Of these diseases one of 

 man and one of cattle occur, and one of fowls is suspected to 

 occur in the United States, while several others would 

 undoubtedly obtain a foothold were they once introduced. 



'It has been estimated by Dr. Mohler (1905) that the 

 cattle tick alone is the source of approximately $40,000,000 

 annual loss in the United States. Mayor (1906) has 

 estimated the annual loss as nearly $100,000,000. 



'These parasites are of considerable importance as external 

 parasites, particularly in the Southern States, owing not only 

 to their irritation and great drain upon stock through removal 

 of blood, but also to their indirect effect as well. In one of 

 Theiler's experiments (1909a) a horse that was infested with 

 Margaropus decoloratiis died as a result of infestation from 

 -acute anaemia due to the withdrawal of blood. Within 

 three days, 14 lb. by weight of ticks which had dropped 

 from this horse were collected, and this amount represented 

 only about one-half of the total number of ticks w'hich 

 engorged upon it. After dropping, their places of attach- 

 ment furnish points at which the screw worm fly {Cln-ysomym 

 )i(nctllaria) deposits its eggs, the maggots from which then 

 readily enter the host. In the Southwestern States the 

 appearance of equines is frequently injured by screw-worms, 

 which gain entrance at the points in the ears where ticks 

 had been attached, burrow, and destroy the supporting 

 cartilage, causing the ears to lop over. This condition is 

 commonl)' known as 'gotched'. Not the least of all is the 

 frequent annoyance which man suffers as the result of the 

 attachment of ticks to his body. 



'The ticks which moult upon the host, instead of having 

 to wait long periods to find another, merely continue sucking 

 blood from the same animal. As a result these ticks repro- 

 duce very rapidly and frequently become of much greater 



importance as e.'cternal parasites than species which drop, 

 to moult. This is the case with the cattle tick. Those 

 which drop to ^ftioult have overcome this great disad- 

 vantage by becoming' more resistant to heat and cold 

 and by having Vgained the power to withstand muoL; 

 longer periods" of fasting. Certain members of the sub- 

 family Ixodinae, while not occurring in such great num- 

 bers on animals as in the case of species which moult ore 

 their hosts — all of which belong to the sub-family Khipicephar 

 linae— are frequently of considerable importance as pests, 

 owing to the fael that the great length of the hypostome 

 permits deep penetration. As the result of this deep pene- 

 tration by the Ixodinae, an inflammation is produced which 

 frequently results in suppuration. Often in the attempt to 

 remove ticks belonging to this class from the body of the 

 host the capituldm is separated from the body of the tick 

 and remains embedded in the host. 



'The periods in the life-history of ticks of particular 

 importance economically, and which should be determined, 

 are: longevitij, or the period required for starvation while 

 awaiting a host; minimum parasitic pjeriod, which is used in 

 connexion with the preoviposition and incubation periods to 

 determine the time that tick free areas may be used after 

 infested cattle are turned in before the areas become infested; 

 iiiaxiriDiiii paiasific jit-riod, or the period required for clean- 

 ing the host of all ticks (except males) when kept in tick-free 

 inclosures; preoriposition period and Minimum incuhation 

 period, used with the minimum parasitic period to determine 

 the time that tick-free lots may be used before becoming 

 infested; stage or stages of inibitiition of infection and the 

 stage or stages in nhich infection is transmitted, i e., in the 

 case of species involved in disease transmission.' 



A Method of Treatment for Borers in Trees 



The following is translated from a note which appeared in the 

 Journal d'Agri'ulture Tropical'- for May last: — 



M. Mieville, a planter at Tonkin, has reported that he 

 has successfully employed the following method of using, 

 rectified benzine against the cotfee tree borer. 



For this purpose a syringe with a strong, sharp point is 

 used: the injection is made as high as possible in the tunnel 

 of the borer so that the benzine may flow down and thus 

 come into contact with the insect, which is immediately killed 

 by being touched by the benzine. 



A few hours after the injection the odour of the benzine 

 will be found to have entirely disappeared, and there are no 

 oil marks or wounds on the tree. 



This method, which has been employed successfully for 

 more than a year by M. Mieville, is said to do away with the 

 necessity for cutting out the attacked parts. 



A New Pest of FiCUS.— A nots in Der PUanzer for 

 May 1912 reports a new pest of Ficus elastica from Dares- 

 Salam, German East Africa. This was observed on the 

 opening leaf shoots, which were otherwise flourishing, and 

 was boring through the young leaves, which later withered^ 

 becoming black at the edges and finally falling. The com- 

 plete stage of the insect is a handsome, yellow beetle, which 

 was described at Amani as Sternotomis hoheniani. This is 

 3 to 4 cm. in length, with clear bluish-green wing cases 

 which are marked with dark-brown, wavy, diagonal linesi 

 The antennae of the insect are 5 to 7 cm. long and curved itj 

 a semicircle from behind. The land of the observer was 

 freed from the pest by systematic search for it, followed b^ 

 its destruction. , 



