Xo. l6.] INSECTS OF CONNECTICUT. 23 



Germs of many intestinal diseases, like cholera and typhoid 

 fever, and of other germ diseases, like bubonic plague and an- 

 thrax, are often carried mechanically on the feet or body of the 

 common house fly, which breeds in and frequents foul matter, 

 and then crawls over food. Both food and foul matter should 

 be inaccessible to flies. 



Certain gadflies are known to carry diseases of cattle. 



Methods of Controlling Injurious Insects. 



The insect enemies of crops may be divided roughly into 

 two classes: (i) those which bite or chew their food, and (2) 

 those which suck out the plant juices for nourishment. To 

 the former class belong those insects which devour portions of 

 the plant, such as the borers, and all leaf-eating forms like the 

 Colorado potato beetle, the elm-leaf beetle, canker-worms, the 

 gypsy moth, and many others. The insects of the latter class, 

 though less evident, are no less destructive, and include the San 

 Jose and all other scale insects, and the aphids or plant lice. 



Pests are commonly controlled by spraying, and by me- 

 chanical means such as traps, barriers, etc. Spraying with in- 

 ternal poisons is the best means of destroying the leaf-eating 

 insects, and for this purpose Paris green and lead arsenate are 

 used. The formulas are given herewith: 



Lead Arsenate Paris Green 



Lead arsenate 3 lbs. Paris green 1 lb. 



Water 50 gals. Lime 3 lbs. 



Water 100 gals. 



Lead arsenate is manufactured in paste form, will adhere 

 much longer to the foliage, remains better in suspension, and 

 causes no injury to the foliage even when used in excessive 

 quantities. 



Paris green, on the other hand, is a dry powder, and may 

 be mixed with land plaster or air-slaked lime and sifted upon 

 the plants. It contains some free acid which is liable to injure 

 foliage, settles quickly in water, and washes off easily. The 

 addition of lime improves the sticking qualities, and neutralizes 

 the free acid, and thus prevents injury to the foliage. 



These poisons may be, and often are, used in Bordeaux 

 mixture in orchard practice. Bordeaux mixture is a fungicide 



