8 BULLETIN 10&8, TJ. S, DEPARTMENT OF AGRICULTURE. 



These records indicate general breeding of Anopheles through- 

 out the course of the stream under natural conditions. Anopheles 

 quadriTnaciiiatus Say is the common species taken, and Anopheles 

 punctipennis Say is second in numbers. It is noted that one collec- 

 tion of Anopheles crucians Wied. was made. The undetermined col- 

 lections represent the Anopheles larvae which were collected but 

 which were not reared to the adult stage. 



For convenience of the survey, the section of the bayou to be 

 cleared of all vegetation was divided into stations 100 yards in 

 length. The distance covered in the experiment was 1,600 yards, 

 nearly a mile. The plants collected from this section, before clear- 

 ing, during July and August, 1915, are shown in Table 2. The plants 

 listed in Table 2 are distributed according to their location and the 

 depth of water in the bayou in Table 3. The plant determinations 

 were made by the Bureau of Plant Industry of this department. 

 The natural conditions in the bayou, including the vegetation, water 

 levels, and other features, are shown in Plate III, Figure 3; Plate 

 IV; and Plate V, Figure 1. 



Table 2. — Plants -from Bayou Walnut, Mound, La., 1915. 



Species. 



Common name. 



Location. 



Spirogyra sp 



Lemna valdiviana, Lemna gibba, Spirodela 



polyrhiza, and Wolffia Columbiana 



Jussiaea diffusa 



Zizaniopsis miliacea 



Cephalanthus occidentalis 



Salix nigra 



Bignonia radicans 



Brurmichia cirrhosa 



Persicaria opelousana 



Phytolacca americana 



Paiiicum colonum 



Asclepias perennis • 



Ampelopsis arborea 



Belonging to family Euphorbiaceae 



Algae 



Duckweed 



Primrose-willow . 

 Aquatic grass.. . 



Buttonbush 



Swamp willow . . 

 Trumpet creeper 

 Buckwheat vine. 



Smartweed 



Pokeberry 



Ditch grass 



Milkweed 



Peppervine 



Spurge 



Submerged. 



Floating on water. 

 In water, roots in bed. 



Do. 

 In channel and along margin. 

 Along margin, overhanging. 



Do. 



Do. 

 Along margin. 



Do. 



Do. 



Do. 



Do. 



Do. 



Table 3. — Vegetation and depth of water in Bayou Walnut, Mound, La., before 

 impounding, July-August, 1915. 



Sta- 





Vegetation. 





Depth of water 



tion. 



Species. 



Common name. 



Location. 



in channel. 





C Lemna spp" 



Duckweed 



Floating on water 



In water 







Jussiaea difiusa 



Cephalanthus occiden- 

 talis. 

 Salix nigra 









Buttonbush 



Bed and margin 





Dam. 



Swamp wiUow 



Margin, overhanging 



6 inches to 11 

 I inches. 





Persicaria opelousana — 



Zizaniopsis mUiacea 



Euphorbiaceae 









Afjnatic grass 



Bed . in water 







Spurge 



Margin 





1 The species of duckweed recorded under Lemna spp. in this list represent Lemna valdiviana, L. gibba, 

 Spirodela polyrhiza, and Wolffia colurnbiana. Submerged algse (Spirogyra; were common along the margtnis 

 in some locations, but the submerged homwort (Ceratophyllum; was not collected in this survey, though 

 it is common in some other locations in the region . 



