59 



make in the sand, and the} T store the burrows with insects for the 

 young to feed upon when the} T hatch. It is not uncommon to find from 

 half a dozen to a dozen specimens of Tabanus in a single burrow, 

 besides other insects. Professor Morgan says that he has taken sev- 

 enteen horseflies, one Syrphid, one Tachinid and one Stratiomyiid 

 from a single burrow. 



Crahro 10-maculatus Say, another wasp, is an expert at catching 

 Tabanids, and the writer often saw them capture the flies and carry 

 them away. None of their nests was found, but it would appear that 

 they have about the same habit in this regard as the Bembecids. 



Erax maculatus Macq. and species of Deromyia were rather com- 

 mon and were often observed feeding upon different species of 

 Tabanidse. 



That chickens ma} 7 become a factor in destroying stock pests was 

 proved b} 7 the fact that the} 7 were often observed following cattle in 

 the pasture, picking off such Tabanids as alighted on the lower extrem- 

 ities of the animals for the purpose of sucking blood. 



METHODS OF CONTROL. 



In my "Tabanidge of Ohio" I suggested the use of kerosene on the 

 surface of the water for killing larvae hatched from eggs deposited 

 over water. Of course this method could not be used in cases where 

 deposition took place over damp ground, as was observed at Cameron. 

 One finds eggs of costal is 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 treatment of insects that is appro- 

 priate 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 materiall} 7 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 windows or striking against the glass and 

 screens; then flew away so -rapidly that the eye could not follow them. 

 August 23, I obtained permission to open the screens from one of the 



