Rural School Leaflet 88i 



time, grow very fast, and become full-grown in two to three weeks. When 

 mature they go to the ground and burrow beneath the surface, where 

 each one makes a snug cell in which it soon changes to a pupa. The pupa 

 remains in its cell for two weeks or longer and then transforms into the 

 adult beetle. These beetles come out of the ground and lay eggs for 

 another generation, which usually is the last one. 



Natural enemies. — Most of us have no idea how often we are aided in 

 our fight against insect pests by our friends the birds, toads, ladybird 

 beetles, flies, wasp-like parasites, and other helpers in the struggle. The 

 enemies of the Colorado potato beetle are many and we are certainly 

 indebted to all of them for the eggs, grubs, and beetles that they destroy. 



Perhaps the most efficient enemies of the potato beetles are the ladybird 

 beetles. At least eight different kinds of ladybirds attack and destroy 

 the potato beetle in som.e of its stages. We should become acquainted 

 with these ladybirds so that we may protect them if possible, and cei- 

 tainly not destroy them. Both the adult ladybirds and their larvae feed 

 on the eggs and grubs of the potato beetle and destroy great numbers 

 of thc-m. 



There are also several kinds of rather large, dark-colored beetles, known 

 as ground beetles, which prey on the potato beetle and its grubs. 



A certain fly, called a tachina fly, lays its eggs on the grubs. The eggs 

 hatch and the maggots bore through the skin of the grub and live inside 

 its body, finally killing it. It is said that the tachina flies are sometim.es 

 so abundant in fields of potatoes that their buzzing sounds like a swarm 

 of bees. These flies must aid us greatly by killing many of the potato 

 beetle grubs. 



Toads and snakes devour m.any of the potato beetles and help greatly 

 in the fight. Birds, too, join in the good work, especially the rose-breasted 

 grosbeak and the bobwhite, or quail. Robins, crows, nighthawks, cuckoos, 

 and other birds also destroy potato beetles. 



Methods of control. — Since both the beetles and the grubs have biting 

 m^outh-parts, they are best destroyed by spraying the potatoes with an 

 arsenical poison. The substance most commonly used is paris green, a 

 very strong poison, and one that is likely to bum the leaves unless quick- 

 lime is added to it. It should be used at the rate of i pound to loo gal- 

 lons of water, with two or three pounds of good quicklime carefully slaked 

 and added to the water. 



Potatoes are subject to the disease known as blight, and most potato 

 growers spray their plants with a fungicide known as bordeaux mixture 

 to control this disease. It is not necessary, however, to make separate 

 sprayings for the blight and for the potato beetle, since by combining 

 the paris green with the bordeaux mixture, i pound to loo gallons, both 



