19 



that go with these, and the isolated depressions filled with water 

 that one often sees in traveling through the domain, we have 

 ^< favorable breeding grounds for these inseets as ean be 

 found anywhere. 



Some of the area inchulod in tlio above consideration could 

 b(- drained, and probably will be some time in the future, but 

 much of it can not be. and, on the whole, it is doubtful if any 

 very large areas will receive relief by drainage, but this remains 

 for future developments to prove. 



I have in mind a certain section, not in the State of liouisi- 

 aua, where mosquitoes and horseflies were exceedingly numerous 

 i^? past years when the country was being ditched and cleared. 

 At the present time this same section is thoroughly unde.r- 

 ■drained. no water stands long enough to become stagnant, and 

 these insects are so uncommon that they hardly ever receive con- 

 sideration. Drainage is a good remedy for horseflies, but there 

 is no use to make such a recomuT^ndation for a country where 

 if. is impossible to put it into operation. 



A section of Louisiana that is especially tj-onV)lcd by horse- 

 flies is the section located in proximity to the gulf coast. This 

 whole country is only a few feet above sea level, and the acre- 

 .^ge of wet and marshy land is very large. Running nearly paral- 

 lel to the shore of the gulf is a series of alternating ridges aud 

 <lepressions. The depressions form extensive fresh water marshes, 

 over a part of which the water stands the year round. The rivers 

 tliat traverse this country are sluggish and at intervals sprea/1 

 <ut into lakes or extensive marshes. Thus various aquatic ani- 

 I'lals find conditions to their liking and are present in abundance. 



Fk;. 11. — Green-hPad horsefly (Tnhanux rostalix/ 

 a. femalp : h. inalp. enlarged Id two tliameters. 



