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undertakes a study of the kind. Some statements bearing on the 

 matter regarding the Tabanidae have appeared from time to time in 

 the literature of economic entomology. If I understand the situation, 

 some hold that it is not advisable to attack these insects in the imma- 

 ture 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 feed- 

 ing habits indicates that they are as apt to feed on beneficial as 

 injurious forms; and since the remedies for horseflies in any stage 

 are, to a degree, unsatisfactory, it seems best to pursue any mode of 

 attack that offers results without reference to the stage in which the 

 attack is made. 



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

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

 stygius Say, in the locality where I have studied it, places its masses 

 of eggs on the leaves of Sagittaria almost altogether, 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 growing scarcely any are to be 

 found. A few counts of the number of eggs composing a mass are of 

 interest. Twenty masses of Tabanus trimaculatus averaged over 500 

 eggs each, and several masses of T. stygius 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 

 man} 7 as 60,000 may be taken in a single hour. Therefore it looks 

 reasonable 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 strongty in color 

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



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

 tory of one species will furnish facts which may be applied in all par- 

 ticulars to the other members of the family. A careful study of each 

 species is almost sure to bring out striking differences, and it is this 

 fact that makes their study interesting and instructive. Eggs may 

 be placed in different situations, for example, over water or over 

 mud, usually according to the species; but at other times it seems 

 according to circumstances. Some species are known to habitually 

 attach their eggs to projecting stones in ripples, others to foliage or 

 any projecting object over stagnant water. It appears that the com- 

 monest species and at the same time the worst stock-pests oviposit 

 over stagnant water or over wet ground. Larvae hatched from eggs 

 placed over water must drop into the water, and therefore a measure 

 of success may be had by using contact insecticides on its surface at 

 hatching time. 



