POND, LAKE, AND STREAM 25 



How frogs hibernate in winter. You have noticed that in 

 late fall, when insects disappear, most birds also leave us 

 and go south. The frogs also disappear at this time. 

 Where do they go ? They hide in the muddy bottoms of 

 pools, lakes, springs, etc. Here at a depth where the frost 

 of winter will not touch them they sleep a death-like 

 sleep. They eat nothing and do not breathe during the 

 whole winter. This kind of sleep is catted hibernation. 

 When the sun and the warm south wind have melted the 

 ice from our waters, the frogs awake and come to the sur- 

 face. The males begin to call their mates by croaking, and 

 soon the females deposit their eggs. 



There is quite a number of different kinds of frogs in 

 our country. Closely related to the common frogs are the 

 Toads and Tree Frogs or Tree Toads. Toads live mostly on 

 land, Tree Toads on trees, but both deposit their eggs in 

 water. Frogs and toads are very useful animals, because they 

 eat a large number of injurious insects. 



16. The Mosquito. 



MATERIAL : Mosquitoes, eggs, and larvae, if possible. The larvae, 

 often called wrigglers, can be found in almost any stagnant pool and 

 in rain-water barrels. Previously observed : How mosquitoes fill 

 themselves with blood; how horses and cattle try to rid themselves 

 of the pest. 



Perhaps you have nrade out most of the life history of 

 the mosquitoes from the observations you have made in 

 your little aquariums. The eggs are laid in little rafts, 

 which float on the water. In a few days the lower ends of 

 the eggs open and the larvae escape into the water. Each 

 one of them has a little tube near the tail end. By means 

 of this tube they breathe. When they are at rest, they 

 hang with their heads down in the water and have their 

 breathing tubes at the surface in contact with the air. 

 The larva lives on decaying matter in the water ; it grows 



