882 Rural School Leaflet 



objects may be accomplished. In this case, because the bordeaux mixture 

 is largely composed of lime, it will not be necessary to add more of this 

 material. 



Some potato growers prefer to apply the paris green dry by mixing it 

 thoroughly with lo to 20 parts dry flour or fine air-slaked lime. Others 

 actually dust the pure poison on the plants in the early morning while 

 the dew is on the leaves. The dust is best appHed by means of a pow- 

 der gun or "dust-spray" machine. In case the pure paris green is used, 

 only a small amount of it should be dusted on the plants because it is 

 likely to bum and kill the leaves. 



The first spraying should be made as soon as the eggs begin to hatch 

 and the young grubs are seen on the plants. In severe cases two appli- 

 cations, a week or ten days apart, may be necessary. 



Arsenate of lead is also a much-used poison for biting insects and is 

 often applied to control the potato beetle. It sticks to the plants much 

 better than does paris green, but, since it is a weak poison, more of it 

 has to be used. The best results will be obtained by using it at the rate 

 of 5 or 6 pounds to 100 gallons of water or of bordeaux mixture. 



OBSERVATIONS FOR PUPILS 



What color are the potato beetles? How many black lines are there 

 along the back of each one? Examine the mouth of a beetle and see 

 whether the hard, black biting jaws can be found. How many are there? 

 How many wings does each beetle seem to have ? What is the difference 

 between these wings? The top ones are called wing covers and are prob- 

 ably not true wings. Watch the beetles flying and see which wings are 

 used for flight. 



Where are the eggs mostly laid ? How many eggs in one bunch ? What 

 color are the eggs? Find out, if possible, how long it is from the time the 

 eggs are laid until they hatch. Beetles may be kept on plants grown 

 in the house. A lantern globe should be placed over the plant and a 

 piece of muslin tied over the top. 



Describe the grubs, or " slugs " as they are often called. What color 

 are they? Do they have any markings on their bodies? What kind of 

 mouth parts do they have? How do they injure the plants? 



Take one of the beetles in the hand and squeeze it slightly. Does it 

 give out a fluid? What color is the fluid? Docs it have an odor? Is 

 the odor pleasant? The liquid issues from the hind edge of the thorax 

 and the front parts of the wing covers. It is probably distasteful to 

 birds and may aid in protecting the beetles from their enemies. The 

 grubs eject a similar fluid. 



