85 



cases where deposition took place over damp ground, as was ob- 

 served at Cameron. One finds eggs of costalis and a number of 

 other species in such places quite frequently. 



With so much standing water to be considered, it would be an 

 immense undertaking to use kerosene for killing adult flies, as sug- 

 gested by Porchinski in Russia, and commented on by Doctor 

 Howard in Bulletin No. 20 (n. s.). Division of Entomology (p. 

 24). It appears that both of the above suggestions, as well as 

 others that might be mentioned, are of most value in special cases ; 

 in fact there is seldom a single remedy in use in economic treat- 

 ment of insects that is appropriate at all times with reference to a 

 particular species or group of nearly related species. 



It is my belief that species of the genus Tabanus have a habit 

 which if better understood might be utilized in trapping them in 

 numbers sufficient to materially lessen their ravages. I refer to 

 their habit of collecting in certain places, as' on buildings, fences, 

 and the like. The habit has been observed at different times and 

 in different places but I saw it more forcibly at the Gulf Biologic 

 Station than at any other place I have observed. The sexes of 

 the last three species of Tabanus mentioned above flew around the 

 station building in numbers, often resting on the siding and win- 

 dows or striking against the glass and screens ; then flew away so 

 rapidly that the eye could not follow them. August 23, I obr 

 tained permission to open the screens from one of the doors to see 

 what the result would be. The screens from a doorway (7 by 5^^ 

 feet) were left open from 10 in the morning to 3 in the afternoon, 

 after which between a pint and a quart of flies of the size of the 

 common costalis were procured from the windows upon the inside 

 of the building. All but about a dozen of these were females, 

 which, as was proved by dissection, had not yet laid their eggs. I 

 believe that a trap might be manufactured that would attract, 

 Tabanids in the same way that they are attracted to the building in 

 question. 



It is worth mentioning that a few females of atratus were taken 

 with the above, so it is probable that if this species had been as 

 numerous as the others just as striking results could have been 

 obtained with regard to it. 



