32 Nebraska State Horticultural Society. 



forty days, during which the great bulk of the new crop of plum cur- 

 eulios is in the ground. The object of this tillage is to turn the pupae 

 out, kill some in the process, and expose the rest to the elements and 

 to birds and insects that prey upon them. Pupae of the plum curculio 

 are extremely delicate, and they are incapable of moving about. In 

 digging for pupae it was observed that admission of air to the burrow 

 invariably caused immediate distress; the pupae would squirm and 

 wriggle as if in pain. Actual trial proved that sunlight was quickly 

 fatal and that exposure on the surface in the shade, on a warm day, 

 would kill in a few hours. It was also demonstrated that birds, ants, 

 and other insects devour exposed pupae greedily. In view of the re- 

 sults obtained in this work with pupae, the definite statement is war- 

 ranted that cultivation with disc 'or harrow will, in great measure, pre- 

 vent the maturation of these insects and at less cost than by any other 

 means. 



"Those who put in practice the suggested means of holding the 

 curculio in check need apprehend no serious trouble from these insects 

 in ordinary years unless injury results through invasion from neighbor- 

 ing orchards that are neglected and that serve as harbors and breeding 

 places. 



"Years of excessive abundance of curculios will doubtless recur, 

 but orchards that are pruned, cultivated, and sprayed are not likely to 

 suffer serious injury. It is the neglected orchards, those affording ideal 

 conditions for insect development, that will suffer most in these years 

 of abundant insects. 



"Curculios, like many other insects, appear to run in cycles. 

 Years of great abundance are, through natural causes, followed by 

 years of comparative scarcity. 



"Persistent application of artificial means of repression will reduce 

 injury to its lowest point in years of scarcity, make the recurrence of 

 maximum injury less frequent, and greatly mitigate the injury in years 

 when insects are most aboundant. 



"It should be remembered that curculios are not the only orchard 

 pests, and that means of repression directed against these insects are 

 equally effective in controlling other insects which are more or less 

 Injurious every year. 



"Spraying is an essential practice for the control of apple scab and 

 other fungus diseases. Arsenical poisons applied with the Bordeaux 

 mixture add little to the expense and are even more effective in checking 

 the ravages of Codlin moth, canker worm and other leaf-eating insects 

 than they are in destroying curculios. The practice of destroying fallen 

 fruit commended as a means of attacking curculio, is equally effective 



