1923 ENTOMOLOGICAL SOCIETY. 49 



time the grapes were in leaf, most of the graperies were literally alive with leaf- 

 hoppers. During the period the overwintering adults were on the vines, there 

 were several heavy washing rains. For example, on May 25th there was a rainfall 

 of 1.23 inches, on June 11th 3.08 inches, and on June 17th 1.38 inches. These 

 rain storms reduced the number of adults to some extent (we found hoppers 

 washed into the soil) but not to a sufficient extent to prevent a serious outbreak. 

 During late June and early July hopper nymphs were present in immense num- 

 bers, as many as 100 to 800 being found on a leaf, and spraying had to be resorted 

 to in order to prevent serious injury. 



The badly infested area extended from the Niagara river to Grimsby — west of 

 Grimsby the insect was abundant in some vineyards, but generally speaking it 

 was of little importance. 



It would not be out of place here to say a word about the campaign which 

 was conducted in the Niagara district against the leaf hopper. By means of 

 meetings, short timely articles and circular letters, practically every grape 

 grower in the district was made acquainted with the leaf hopper situation and 

 also with the methods of combating the pest. The success we had in dissemin- 

 ating this information was due largely to the co-operation of the Niagara Dis- 

 trict Grape Growers' Association, a selling organization with a membership of 

 over 900 growers, covering over 90 per cent, of the total acreage of grapes. The 

 association held meetings at different points for the purpose of discussing the 

 leaf-hopper outbreak, and they sent out copies of the short circular letters, 

 which we prepared, to all their members. As a result of this publicity campaign, 

 most of the grape growers between the Niagara river and Grimsby sprayed their 

 vineyards. In some of the worst affected sections from 95 per cent, to 100 per 

 cent, of the growers treated their vines. 



Life History. 

 The Overwintering Adult. 



Description: See page 55. 



Hibernation. The Grape Leaf-hopper passes the winter in the adult 

 stage under fallen leaves, logs and rubbish; among clumps of grass and weeds; 

 and in decayed tree stumps, etc. Woods and waste places, neglected road 

 sides, headlands and ditches; old fence rows and hedges all afford the insect 

 favourable quarters for wintering. 



Activities in Early Spring. This spring during March and early April, 

 the adult hoppers were quite active in their hibernating quarters on mild days, 

 when the temperature was in the neighbourhood of 42 degrees F. to 50 degrees F. 

 They jumped readily when disturbed; however, they did not commence to 

 emerge from hibernation until the last week in April, about the time grape 

 buds were commencing to swell. As shown by cage experiments and field obser- 

 vations, they continued to emerge over a period of three weeks. 



Spring Food Plants. As there are no grape leaves at the time of emerg- 

 ence, the hoppers after their long winter siege are forced to feed on other plants. 

 This spring they were observed first on the leaves of grasses, chickweed, dande- 

 lion, strawberry and raspberry, but later on they were found feeding on a large 

 number of other plants, viz.: Sweet cherry, sour cherry, apple, peach, plum, 

 white sweet clover, alsike clover, lucerne, yarrow, catnip, sheep sorrel, Canada 

 thistle, shepherd's purse, hound's tongue, common plantain, wild geranium, 

 bellwort, trillium, violet sp., daisy fleabane, dandelion and curled dock. Straw- 

 berry, raspberry and sweet cherry, however, appeared to be the favourite food 



