104 Insects and Disease 



be covered with a film of kerosene which will kill all 

 the larvae in the water when they come to the sur- 

 face to breathe, and will also kill the females when 

 they come to deposit their eggs. The vent to open 

 cesspools should be thoroughly screened or the 

 surface of the water kept well covered with oil. 

 Water standing in any vessels in the yards should 

 be emptied every week or ten days and the old tin 

 cans destroyed or hauled away. In fighting these 

 domestic species you need be concerned only with 

 your own yard and that of your near-by neighbors. 

 Other species, while also rather local in their dis- 

 tribution, fly much farther than the really domestic 

 ones. In fighting these the region for a consid- 

 erable distance around must be taken into consid- 

 eration. Watering- troughs (Fig. 95) that are left 

 filled from week to week, the overflow from such 

 places, and the tracks made in the mud round 

 about them (Fig. 96), small sluggish streams, irri- 

 gating ditches, and small ponds or lakes not sup- 

 plied with fish are excellent breeding-places for sev- 

 eral species of mosquitoes including Anopheles and 

 others. The remedy at once suggests itself. The 

 watering-trough can be emptied and renewed every 

 week during the summer time, the overflow can be 

 taken care of in a ditch that will lead it away from 

 the trough to where it will sink into the ground, the 



