222 
Psyche 
[December 
ever. Females occasionally moved their abdomens slowly from side 
to side or rocked back and forth as males pressed at them. One fe- 
male repeatedly placed a hind leg on a male and pushed it away over 
a period of 45 minutes. Two females lifted their abdomens upwards 
but refused to permit the male aedaegus to enter their genital open- 
ing. 
The Aggregation and Dispersal of E. conspersus 
This stinkbug species often forms groups. As previously noted the 
courtship fern usually carried several bugs (during the period from 
27 May to 1 June) although the exact number fluctuated from o to 
21. Although the bugs were not marked it is at least possible that 
the same individuals came and went returning to the fern several 
times. Six meters away another bracken fern was found with an- 
other group of bugs. This aggregation was a durable one lasting 
from late May to 1 July and probably several days more. Again the 
number of stinkbugs present varied a good deal reaching a maximum 
of 30 individuals on 21 June including 8 mated pairs at 20.30. 
Given the considerable amount of sexual activity which occurred 
in these first generation groups I initially felt that their function 
was exclusively sexual in nature. However, I later discovered that 
aggregations were also formed by nymphs and second-generation non- 
breeding adults. Groups of 5-6 late instar nymphs could be found 
basking on the same leaf together, some even with their heads under 
the side of a companion, an action reminiscent of the abdomen lifting 
behavior of courting males. As fall neared large numbers of bugs 
(up to 61) occurred on a single fern. Smaller contact groups of 
5-10 individuals were common (Fig. 4) and one large tightly clumped 
cluster of between 15 and 35 bugs was found on exactly the same 
portion of a blackberry stem on various dates from 28 September to 
17 October. 
At the same time not all individuals showed a tendency to clump 
together in semi-permanent groups. On the contrary many E. con- 
spersus were highly active and could be seen walking substantial dis- 
tances along blackberry stems from one plant to another. On warm 
days in the afternoon bugs were often seen flying five to ten meters. 
Of 30 bugs marked on 21 May, I could find only 2 the next day. 
The apparent mobility and dispersal of many stinkbugs contrast 
sharply with the seeming stability of some groups. 
Moreover, the bugs, despite sometimes forming contact groups, also 
could demonstrate a degree of anti-social behavior. Stinkbugs were 
seen kicking at each other when touched by a companion. Once one 
