Dec. i, 1923 
The Three-Banded Grape Leafhopper 
423 
rounding tissue checks growth of wood and fruit, weakening the vine. 
Fruit from badly infested vines shows the typical inferiority; it does not 
ripen properly, is poorly colored, low in sugar content, and stained with 
excreta. When the wood is not normally ripened, part of the buds or 
whole bearing canes may winter-kill. Although the winter of 1922-23 
was comparatively mild, minimum temperatures having been above zero 
in the Sandusky district, instances of serious freezing back of bearing 
canes were observed in several northern Ohio vineyards which had been 
heavily irifested with leaf hoppers in 1922. This injury was apparently due 
to a combination of causes—immature wood, caused by leafhopper injury 
and a heavy crop of fruit (which ripened poorly), and lack of moisture 
in the soil before freezing, the fall months having been unusually dry. 
Hibernation. —After the first heavy frosts the adults move about in 
search of food and cover, congregating in great numbers on sheltered 
vines where the grape foliage is still green, and remaining as long as food 
can be obtained. Many travel to surrounding fields or borders, which 
furnish especially favorable hibernating conditions during winter. 
During the fall migration, if it can be so called, the species shows a 
marked tendency to congregate about near-by buildings and in localities 
protected from wind. Adjacent vineyard areas are commonly centers 
of heavy infestation during summer. A heavy migration commenced in 
1922 on October 13, after the first killing frost. Adults were numerous 
on grape foliage in sheltered places as late as the third week in November. 
Vast numbers, in some localities apparently the greater proportion, 
remain in the vineyards under the vines, where they can be found at any 
time during the winter. They are generally distributed over the vine¬ 
yards under partly decayed moist grape leaves in depressions in the ridge 
of earth under the trellis. On January 29, 1923, between 600 and 700 
live adults were obtained from an area of 1 square foot under a Concord 
vine in the center of a large vineyard, but on the same day only a few 
specimens could be found in an adjoining alfalfa meadow. 
The term hibernation is used only in a general sense, as overwintering 
adults merely keep in hiding under cover during cold weather and are 
dormant only at temperatures below freezing. At air temperatures 
only a few degrees above freezing they have been observed hopping about 
actively on the frozen ground after the covering of grape leaves had been 
removed from about the base of the vines. 
Feeding of adui/ts and spring activity. —As with Erythroneura 
comes , the three-banded leafhopper feeds on a variety of plants before 
the grape leaves appear in spring, but once it begins feeding on grape 
foliage it does not change until the leaves are destroyed by frost. Simi¬ 
larly the species has not been found breeding on any plant other than 
grape. The general movement to grape foliage in the spring, however, 
seems to take place somewhat later than with certain other species. 
On South Bass Island, Lake Erie, in 1921, new shoots and grape leaves 
in several vineyards were found to be severely injured by large numbers 
of overwintering adults of E. vulnerata var. vulnerata on May 18. The 
three-banded leafhopper (E. tricinda var. cymbium) was found to be 
present on the ground among fallen leaves in large numbers, but was not 
found abundant on the new growth until after June 10. After that date, 
it remained the predominant form until the close of the season. During 
1922, nymphs of E. corner were recorded in vineyards considerably earlier 
than nymphs of E. tricinda var. cymbium . 
71686—24 - 4 
