C. E. Abbott.
Death-feigning in Anax junius and Aeschna sp.
Psyche 33(1):8-10, 1926.

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8 Psyche [February
DEATH FEIGNING IN ANAX JUNIUS AND AESCHNA SP.
BY C. E. ABBOTT,
Elgin, Illinois.
In reviewing the literature on death feigning of insects, I was unable to find anything relating to this peculiar behavior in dragon-fly larvse. The Severins have worked with two species of water-bugs, but this, and the work of Holmes on another aquatic Hemipteron, Ranatra, are the only references available on this phenomenon in aquatic insects. The theory of Holmes concern- ing the death feigning of insects is an interesting one. He regards it as an overdeveloped thigmotaxis.
The idea of working with Anax and Aeschna readily sug- gested itself because of the ease with which these insects were obtained and the fact that work was being done with them in quite another group of experiments. It was observed that, when the animals were taken from the water and placed on a solid object, they remained motionless, with the cloaca1 valves closed, and their legs pressed closely against their sides. To put the INDIVIDUAL TESTS
Individuals
Trials
1 min.
30 sec.
30 sec.
18 min.
7 min.
45 sec.
2 min.
9 min.
1 min.
45 sec.
1 min.
45 sec.
5 min.
13 min.
30 sec.
11 min.
3 min.
30 sec.
no
*esponse
2 min.
45 sec.
5 min.
3 min.
30 sec.
5 min.
12 min.
45 sec.
IV
2min.
30 sec.
4 min.
30 sec.
. 2 min.
15 sec.
1 min.
2 min.
1 min.
30 sec.
9 min.
5 min.
30 sec.
10 min.
45 sec.
4 min.
1 min.
30 sec.
6 min.
10 sec.
14 min.
30 sec.
18 min.
7 min.
30 sec.
13 min.
30 sec.
2 min.
3 min.
17 min.
9 min.
45 sec.
22 min.
2 min.
3 min.
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9261 Death Feigning in Anew Junius and Aeschna 9 Duration of Successive Feints
Individuals
Trials
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1.
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7.
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1.
2.
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2 min. 30 sec.
1 "
30 "
30 "
35 "
5 min. 30 sec.
3 "
2 min.
1 "
1 "
30 sec.
45 "
45 "
15 "
45 "
45 "
45 "
7 min.
6 " 30 sec.
4 "
3 "
3 "
1 "
15 "
5 min, 30 sec.
1. " 30 "
3 "
1 "
45 "
5 "
3 "
2 "
2 "
1 "
*
6 "
2 "
1 "
1 "
45 sec.
c
--
12 in.
11
1 "
2 " 30 sec.
9 min. 30 sec.
4 "
13 "
6 min. 30 sec.
3 "
3 "
1 "
1 "
30 '(
1 "
animal back into this condition, it was only necessary to gently stroke its sides. In experimenting, the larvae were placed on wet sand. One group of tests was made simply to determine the length of individual feints, and another set was made to discover the duration of successive feints. It thus appears that the duration of individual feints varies .
a great deal, and that the duration of feints in rapid succession tends to decrease.
This is in accord with what is known of the phenomenon in other insects.
I wish to take this opportunity of thanking Dr. W. S. Marshall of the Zoology department for his co-operation and suggestions in this and other experimental work.



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Pysche
LITERATURE.
[Fe brua'i
The instinct of feigning death.
Pop. Sci. Mon. LXXII,
p. 179. (1908).
Severin, H. H. P. and H. C.
An experimental study of the Death-Feigning of Belostoma (=Zaitha Auct.) flumineurn Say and Nepa apiculata Uhler. Behavior Monog, I, 20.3, 44 pps., 1 pi. (1911).



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