86 



SOME ECONOMIC CONSIDERATIONS WITH REFER- 

 ENCE TO THE TABANIDAE.* 



BY JAMES S. HINE. 



An interesting entomological study is that which has for its ob- 

 ject the separation of beneficial and injurious species, but it is 

 safe to say that one is almost sure to meet with perplexing ques- 

 tions when he undertakes a study of the kind. Some statements 

 bearing on the matter regarding the Tabanidas have appeared from 

 time to time in the literature of economic entomology. If I un- 

 derstand the situation, some hold that it is not advisable to attack 

 these insects in the immature stages on account of the predaceous 

 habits of the larvae. So far as the study of this latter stage has 

 advanced, all that bears on feeding habits indicates that they are 

 as apt to feed on beneficial as injurious forms; and since the reme- 

 dies for horseflies in any stage are, to a degree, unsatisfactory, it 

 seems best to pursue any mode of attack that offers results with- 

 out reference to the stage in which the attack is made. 



By studying the egg-laying habits of different species, it is re- 

 vealed that there is a certain uniformity in regard to the matter. 

 Tab anus siygius Say, in the locality where I have studied it, 

 places its masses of eggs on the leaves of Sagittaria almost alto- 

 gether, and since these plants have a tendency to grow in patches, 

 one often finds a small area where these eggs are very abundant, 

 while but a short distance away where the plants may not be grow- 

 ing scarcely any are to be found. A few counts of the number of 

 eggs composing a mass are of interest. Twenty masses of Ta- 

 banus triuiaculatus averaged over 500 eggs each, and several 

 masses of T. stygins averaged almost as many. From a desire to 

 know how many eggs could be collected in a given time, I have 

 found that it is easily possible to find places where as many as 

 60,000 may be taken in a single hour. Therefore it looks reason- 

 able that some method of gathering the eggs might produce good 

 results, especially when we consider the large size of the masses 

 and the fact that these masses usually contrast very strongly in 

 color with the objects to which they are attached. And again, the 

 fact that a small area of marshy ground or stagnant water in some 

 regions may be the only location in a large scope of country that 

 offers favorable conditions for the oviposition of the Tabanidge. 

 It is not to be supposed that an account of the habits and life 



♦Reprinted from "Proceedings of the Sixteenth Annual Meeting of the Asso- 

 ciation of Economic Entomologists."— U. S. Dept, Agr., Division of Entomoloey 

 Bull. No. 46, Washington, 1901, pp. 23-25. 



