24 BULLETIN 964, U. S. DEPARTMENT OF AGRICULTURE. 



NATURAL ENEMIES. 



Repeated observations have shown that because of the alertness 

 and saltatorial habits of the nearly grown nymphs and adults of the 

 garden flea-hopper their chances of being attacked by natural enemies 

 are somewhat meager. The nymph in the earlier stages, however, 

 is known to be less active and is frequently attacked by the larva of a 

 small red predacious mite of the family Erythraeidae. The writer 

 also reared a number of egg parasites which have been determined 

 by A. G. Gahan as representing the following species: 



Anaphes perduhius Girault. Tetrastichus sp. 



Gonatocerus sp. Anagrus armatus nigriventris Gir. 



Westivoodella americana Aslim. Abbella suhfl.ava Gif . " -- ■ - 



These species have been reared from the eggs of the garden flea- 

 hopper collected from the alfalfa fields where the outbreaks occurred, 

 and the parasites were believed to have rendered an appreciable 

 amount of good. 



REMEDIAL AND PREVENTIVE MEASURES. 



Since the garden flea-hopper has an extremely wide range of food 

 plants, though alfalfa is one of its favorite hosts, rotation as a remedy 

 would be out of the question. Clean culture, however, to prevent 

 hibernation in weeds and trash was found to result favorably in 

 controlling the overwintering adults and is the most adequate means 

 thus far devised of reducing the numbers of the pest. 



In alfalfa fields where outbreaks of the garden flea-hopper occurred 

 it was observed that timing the removal of the crop so as to destroy 

 the eggs was a vital factor in control. Although a small percentage 

 of the eggs is laid near the ground, the larger proportion is deposited 

 in the delicate leaves and petioles. Some of these leaves containing 

 eggs drop to the ground, it is true, and in numerous cases these eggs 

 hatch; nevertheless, timely cutting will remove the larger number, 

 and this measure is recommended in controlling an outbreak. 



DUSTING AND SPRAYING TESTS IN THE FIELD. 



A dusting experiment was conducted in one of the alfalfa fields 

 where an outbreak of the garden flea-hopper occurred, the damaged 

 crop being cut and removed from the infested field. An area of 100 

 square feet was selected and treated thoroughly with a mixture of 

 air-slaked lime and flowers of sulphur in equal proportions. The 

 mixture was thoroughly applied with a hand duster, one application 

 being made in the morning and another at midday. Repeated 

 observations by the writer after the dusting was completed failed to 

 show that the treatment had been effective on any stages of the flea- 

 hopper. 



In the same field a plat of similar size was treated with a spray 

 solution composed of potassium sulphid and water at the rate of 1 



