INSECTS AND BIRDS. 285 



months in summer, all ticks in the field will die. Be- 

 fore cattle are again placed in this " tick-free " field 

 they are also cleaned of ticks, usually by greasing them 

 with crude oil. When both the cattle and the pasture 

 have been made tick-free no more ticks will get on the 

 cattle unless a tick-infested animal is brought to the 

 pasture. There are many modifications of the pasture 

 rotation method. Full descriptions of them can be 

 found in the bulletins published by the State Experi- 

 ment Stations. 



EXERCISE. Have one of the pupils secure several engorged ticks 

 from a gentle cow and bring them to the school. Place them in 

 an open-mouthed bottle or small dish until eggs are laid. Note 

 the small size of the eggs and their abundance. Place some of the 

 eggs in a clean glass bottle and close the mouth of the bottle with 

 cotton. Keep in a warm room until the eggs hatch. How many days 

 are required? Through the sides of the bottle examine the baby 

 ticks. How many legs have they? Do not open the bottle of seed 

 ticks in the schoolroom. 



SECTION XLV. THE COTTON WORM OR COTTON 

 CATERPILLAR. 



By PROF. WILMON NEWELL, 

 Texas State Entomologist. 



The cotton worn, or cotton leaf-worm, is well known 

 to every cotton planter. The bluish-green caterpillars, 

 or " worms," appear in the cotton fields in middle or 

 late summer, and feed upon the leaves and squares. 

 When numerous they quickly strip the plants of all 

 foliage, and the cotton crop is severely curtailed. In 

 the southern part of the Cotton Belt five or six genera- 

 tions of the caterpillar are produced each summer; in 

 the northern part only two or three broods appear. 



Life History. The adult insect is an olive-gray 

 moth measuring about one and one-quarter inches 

 across the wings when in flight. The moth is active 

 only at night, and during her lifetime lays from 300 to 

 500 eggs. These eggs hatch, in from 3 to 8 days, into 

 small greenish larvas marked with small black dots. 



