TWENTY-SIXTH REPORT OF STATE ENTOMOLOGIST 37 



leafhopper hibernates as an adult, flying in the spring to the 

 vines where it lays its eggs within the leaf tissue. When these 

 eggs hatch the nymphs join the adults in their depredations. 

 At Bozeman there is apparently one complete generation and a 

 partial second. 



The best control was obtained by spraying the vines shortly 

 after the first nymphs became noticeable on the under sides of 

 the leaves. Treatment before this time did not give satisfactory 

 results, and spraying after this period was too late to prevent con- 

 siderable injury. If the leaf hoppers are abundant, though, spray- 

 ing is advisable at any time during the summer. 



While community action against these insects is no doubt de- 

 sirable, that it is not essential can be seen from figure 6. This shows 

 how a part of a large Virginia creeper was protected by one ap- 

 plication of spray. The picture was taken in September and the 

 part of the vine to the left has been completely defoliated. The 

 sprayed portion is still green. 



The greatest degree of control was obtained with the following 

 mixture: 



1 2/3 ounces nicotine (Black Leaf 40) 



8 ounces summer oil emulsion 



5 gallons water 



The oil should be placed in a suitable container and the water 

 added slowly and with continuous agitation until a uniform milky 

 emulsion is obtained. The nicotine is thoroughly mixed with the 

 emulsion just before the spray mixture is to be applied. Its effect 

 is rapidly lost if the mixture is allowed to stand for any length of 

 time. 



If a summer oil is not available it may be made as follows: 

 To one part of skimmed milk add very slowly two 

 parts of a good grade No. 10 viscosity lubricating oil such 

 as may be purchased at any filling station. The mixture 

 must be thoroughly agitated all the while that the oil is 

 being added. An electric kitchen mixer or a common egg- 

 beater may be used for this purpose. If properly made, the 

 resulting emulsion is heavy and white with no evidence of 

 free oil. 



The spray mixture should be liberallly applied to both sides 

 of the vines if possible. The under sides of the leaves should be 



