298 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



40 added at the rate of IX pints to every 100 gallons of spray.^ Ap- 

 plications were made June 17, June 28, July 7 and July 19, the spray 

 being applied with a ten -gallon capacity hand ptunp. 



Three plants were selected, one from each variety and one as a 

 check, and the hatching leafhoppers were counted and killed daily. 

 A total of 822 nymphs hatched from the Green Mountain, 864 from 

 the Irish Cobbler, and 2573 from the check, the ratio of the counts on 

 the unsprayed as compared with the sprayed being about three to one. 

 This did not represent the actual control as the young first instar 

 nymphs were removed directly after hatching and before the Bordeaux 

 mixture could act on them. That this must have been the case was 

 illustrated by the fact that on other sprayed plants only a few of the 

 nymphs in the fourth or fifth stages were found. This indicated that 

 comparatively few of the young survived after hatching from these 

 plants and only because they were able to feed on unsprayed leaves, 

 many of which could be found on the vines no matter how carefully 

 they were sprayed. These daily counts also showed that this material 

 was cumulative in its effects, there being a decrease in the leafhopper 

 population which continued from day to day due, as cage tests showed, 

 to the repellent action on the ovipositing females and the toxicity to 

 the nymphs. 



EXPERIMENTS ON THE BIOLOGY AND TIPBURN DISEASE OF 

 THE BEAN LEAF-HOPPER WITH METHODS OF CONTROL. 



{EMPOASCA MALI LE BARON) 

 By A. H. Beyer 



The Bean Leaf -Hopper is generally distributed over the State of 

 Florida, and is one of the most important insect enemies of the bean 

 and other crops growing in the trucking sections of the state. The 

 northern portion of the state, including Gainesville where the writer 

 conducted his biological studies and experiments on control, during 

 1921, there was found to be an over- wintering period, while southern 

 Florida including the latitude at least as far north as Plant City, where 

 it was quite apparent that there is no over-wintering period. According 

 to a survey which was made in early February the following facts were 

 revealed : all stages of the life cycle were collected from the castor bean 

 host, and an outbreak was recorded on garden beans {Phaseolus vulgaris) 

 at Miami, Florida as early as March 24. The earliest outbreak in the 



iThe addition of nicotine sulfate did not increase the toxicity of the Bordeaux 

 sufficiently to make any difference in counts between the two plots. 



