66 
Psyche 
[June 
leaved maples ( Acer negundo L.) growing under and around it to 
the south and east. Northwest is an old apple tree ( Pyrus malus L.). 
Because of these surrounding trees, there are few branches of Juglans 
B accessible from the ground. 
In the fall of 1956 large numbers of Corythuca juglandis (Fitch) 
were observed on Juglans A. This suggested the field work that was 
initiated the following spring and expanded to a study of local Tingid 
populations. During the 1957 season collections were taken from 
Juglans A at near weekly intervals from late May until early October. 
In 1958 and i960, with assistance from the grants mentioned, 
regular weekly collections were made from both butternuts through- 
out the periods of lace bug activity. 
For reasons not yet clear the infestation has been consistently heavier 
on Juglans A. Two conditions may have some bearing on this. As 
already noted, Juglans A has several leafy branches near the ground 
and there is a heavy sod of timothy ( Phleum pratense L.) orchard 
grass (Dactylis glomerata L.) and other herbs beneath this tree. 
The clumps of grass culms and other low vegetation possibly provide 
a favorable shelter for overwintering lace bug adults. Just under 
Juglans B the ground is nearly bare because of heavier shade from the 
surrounding trees, and only on the east are a few branches within 
reach from the ground. Curiously, these two trees, with only a 
grassy field between them and the minor differences cited, support 
very different population concentrations of this lace bug as the graphs 
clearly show (Figures I-IV). 
In 1957 seventeen collections were made and a total of 266 
specimens taken. Of these 176 were females and 90 were males for a 
sex ratio of almost 2:1. Unlike the three season record for C. mol- 
licula , however, (Bailey, 1963) totals for C. juglandis for the same 
three seasons are 1696 $$ and 1505 cf <$ — or a ratio of roughly 5 14. 
in favor of the females. With more collecting this would perhaps 
approximate even more closely a 1 :i relationship. Since the population 
trends for 1957 are otherwise similar to the subsequent studies, and 
because the interval between collections was not as regular that year, 
Explanation of Figures I, II, III and IV. 
These figures present graphically the population trends for Corythuca 
juglandis (Fitch) on two specimens of Juglans cinerea L. for the two years 
specified. The curves are based on actual numbers (indicated on the left) of 
adult lace bugs collected on the dates given at the bottom of each figure. In 
each figure the uppermost curve represents the totals of all population samples 
for the season. Differences in the seasonal distribution of females and of 
males in these same collections are shown by the middle and the lowermost 
graphs respectively. 
