VOLUME ELEVEN NUMBER FOUR
JOURNAL
OF
ENTOMOLOGY
AND
ZOOLOGY
DECEMBER, 1919

PUBLISHED QUARTERLY BY
POMONA COLLEGE DEPARTMENT of ZOOLOGY
CLAREMONT, CALIFORNIA, U. S. A.

CONTENTS

Page
Notes on the Behavior of the Social Wasp Polistes—Horace Gunthorp[63]
Biology of the North American Crane-Flies. V. The Genus Dicranoptycha—Charles P. Alexander[67]
The Central Nervous System of Nucula and Malletia—W. A. Hilton[75]

Entered Claremont, Cal., Post-Office Oct. 1, 1910, as second-class matter, under Act of Congress of March 3, 1879

Journal of Entomology and Zoology

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The Journal of Entomology and Zoology
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Notes on the Behavior of the Social Wasp Polistes

HORACE GUNTHORP
Washburn College, Topeka, Kans.

One day last September the writer picked up a nest of the common social wasp, Polistes, which had been detached from its support, and placed it upon his desk. A short time later he was attracted by a scratching sound, and discovered that one of the wasps was just beginning to cut the cap from its cell preparatory to emerging. During the next few days a series of observations were made and notes taken covering the behavior of the wasps which emerged from their cells during that period. Miss Enteman[A] has made a careful study of the instincts of the social wasps, and while the observations recorded in the present paper are largely corroborative of her work, some interesting details are here added.

The cutting of the cap of the cell occupied some time, and extended around four-fifths of its circumference, the remaining one-fifth being gnawed and partially chewed through so that it was flexible enough to act as a hinge for the cap. After the cap was sufficiently cut away, the wasp started to slowly work itself out, pushing up the top of the cell like a trap door as progress was made. A good deal of effort was required to get the body out until the front legs were freed. Then the wasp had more purchase and progress was somewhat faster until the second pair of legs came out. After this slight effort seemed to be necessary for the completion of the operation.

For the next thirty minutes careful observations were made of the movements of this wasp in order to ascertain its first reactions. It is evident that they would be somewhat modified from what they are here recorded if the colony had contained the queen and other workers, as this specimen had the run of the entire nest, and none of its movements were effected by those of other individuals. It is equally evident that all stimuli came from within, or from contact with the nest, and not from suggestions received from other individuals or from contact with them. The following is the record made at one minute intervals, beginning with the time the specimen left its cell:

8:06. Specimen emerged from its cell.

8:07. Cleaned its front legs in its mouth and its antennæ with its front legs.

8:08. Moved around some. Rubbed its wings with its hind legs and spread them out twice.

8:09. Cleaned antennæ and front legs.

8:10. Swung abdomen back and forth, and brushed its wings. Moved around the nest rapidly and waved the antennæ, but all movements were jerky.

8:11. Explored nest, occasionally rubbing abdomen with legs.

8:12. Explored nest.

8:13. Explored nest. Movements unsteady. Cleaned antennæ and front legs.

8:14. Explored nest, in the course of which it went over the edge on to the back side, but immediately returned to the under side. Cleaned the front legs and antennæ, and then the hind legs.

8:15. Spread out the wings. Cleaned the antennæ.

8:16. Cleaned abdomen.

8:17. Crawled on top or back side of nest again and stayed there. Cleaned wings and abdomen.

8:18. Explored top. Cleaned front legs and antennæ.

8:19. Stood still. Occasional movement of head, antennæ or abdomen.

8:20. Same as 8:19.

8:21. Began to explore again, becoming quite lively. Antennæ constantly waving.

8:22. Same as 8:21, but extended its travels to the under (cell) side of the nest.

8:23. Left the nest entirely and began to walk around the surface of the desk.

8:24. Started to climb a bottle that was some six inches from the nest. Antennæ still waving.

8:25. On the neck of the bottle, two inches above the surface of the desk. Cleaned front legs and antennæ.

8:26. Quiet except that it spread its wings once.

8:27. Still on neck of bottle. Moved its head and antennæ back and forth.

8:28. Slight change in position. Antennæ were still waving. Rubbed its wings, spread them, and then rubbed them again.

8:29. Rubbed its hind legs together vigorously.

8:30. Spread wings once, then rubbed them and the abdomen with the hind legs. Rubbed the hind legs together, and finally rubbed the right wings vigorously.

8:31. Moved around some, occasionally stopping to rub the right wings.

8:32. Explored the neck of the bottle.

8:33. Same as 8:32. Cleaned antennæ.

8:34. Same as 8:33.

8:35. Stood still but continued to clean antennæ and front legs.

8:36. Climbed up and explored the cork of the bottle.

8:37-8:40. Stood still on the cork, occasionally moving its jaws.

At 8:40 the nest was placed against the cork and the wasp immediately crawled onto it, but seemed restless. As the nest has a faint, but distinct, odor of honey, it was probably attracted to it through the sense of smell.

The next morning the specimen was nowhere in sight, but forty-eight hours later it fell out of a loose-leaf binder that had been lying on the desk. It seemed to be as active as when seen two days before. Some time during the second night after the appearance of the first specimen, that is, when it was some thirty hours old, a second individual emerged. This one was discovered on a pile of books two feet from the nest where it had evidently crawled soon after emerging.

As soon as the first specimen was rediscovered, that is, when it was sixty hours old, the second wasp then being thirty hours old, the two were placed on the nest, and this in turn was placed on a book. They both started on tours of observation, and every time they came in contact with each other they made sudden starts and jumps to avoid an evidently startling new object, meanwhile violently waving their antennæ and often cleaning these organs after such contact. Dr. Enteman says, "All wasps possess the instinct of fear. This ... is readily overcome by the frequent appearance of the awe-inspiring object." This is true, because they were evidently on familiar terms with each other in half an hour, and paid very little attention to the frequent meetings which before had apparently distressed them. They wandered freely over their nest and the top surface of the book on which it was placed, but did not attempt to climb off the latter.

At 12 o'clock, four hours later, a third wasp had appeared, and none of the specimens seemed to be disturbed by the presence of the others. When the nest was first picked up, one cell containing a well formed pupa was uncapped. This specimen was then alive, but it may have been dead at the time of this observation. In either case, it had been dragged out of its cell, decapitated, and the front legs torn off. No trace of the head was found, but the body and legs were on the book about one inch from the nest. Whether this act was connected with the hunger of the wasps themselves or with the first development of the instinct of feeding the larvæ in the nest, which Miss Enteman says begins without imitation, is not clear.

At 2 p. m. (two hours later) the colony was placed out of doors, still on the book. Two of the wasps soon left the latter, and settled near it, keeping very quiet for half an hour. The third kept climbing over and around the nest. At 2:30 one of the two wasps returned to the nest.

At 3 p. m. two of the specimens were on the ground near the porch. They made only short flights, resembling jumps with the wings assisting, this being true even when they were disturbed. The third wasp was beside the colony, chewing on the decapitated pupa, probably getting some nourishment from it in the process.

During the afternoon the nest was disturbed, and at 6 p. m. all three specimens had gone from the porch. One was found wandering aimlessly on a canna leaf near by. It did not seem to be able to fly well. The other two had disappeared entirely.

The nest was saved and several days later a fourth wasp appeared. It was a very lively specimen, and spent the first few hours actively exploring the nest. It seemed of a very nervous disposition, being more easily disturbed than any of the others had been. Every time the nest was picked up, it would start for the fingers or forceps holding it. At one time it was observed with its whole body in a cell, head downward, evidently examining the interior. After staying close to the nest for a day, it began to fly around the floor of the room, paying no more attention to its former home. Even when it was placed on or near it, it would almost immediately crawl or fly away. Its flying was erratic, and seemed to lack power, but it got along much better than any of the other three had done.

From the above observations it would appear that the movements of the wasp recorded at one minute intervals after emergence from its cell were probably reactions due to the discomfort of the drying and hardening of the tissues. At first the wasps apparently had very little, if any, home instinct. The only things to indicate that they had any were the facts that the first specimen so readily left the cork on which it was sitting and went back to its nest when the latter was held near it, and the fourth wasp stayed on or near the nest for the first twelve hours. But all the specimens observed left the nest the first night and showed no intention or disposition to return. The presence of a second wasp seemed to bring the home instinct into existence more forcibly, as the first and second wasps stayed with the nest for six or seven hours when they were returned to it together, while the fourth one repeatedly left the empty nest almost at once when it was returned to it. But this instinct was seemingly not very strong, as they soon wandered away when placed out of doors. They seemed to have no idea as to how to carry on the work of the colony, but wandered aimlessly over it. Perhaps this was due to the fact that they were too young, as Miss Enteman says the development of the nursing instinct is usually manifested "any time after the first half day of imaginal life," but was observed in some neuters as young as four hours, while in others it was delayed for two weeks.

While the above observations are admittedly too few from which to draw definite conclusions, they seem to warrant the following assumptions, the first three of which are quoted from Miss Enteman, and hence are simply corroborative of her work:

1. "All wasps possess the instinct of fear. This is especially strong the first few days after emergence, but is readily overcome by the frequent appearance of the awe-inspiring object.

2. "In a sense, the wasp remembers. This is indicated by the manner in which it accustoms itself to the sight of strange objects, and by its behavior when a change is made in its nest or surroundings.

3. "It shows considerable individual variability, both as to time and manner of its response to stimuli."

4. After emergence, the first reactions are associated simply with the discomfort of the hardening of the tissues.

5. It has marked curiosity, as shown by its repeated inspection of its nest and other familiar objects.

6. The "home instinct" seems to be slight when the wasp is alone, but becomes stronger when two or more are on the same nest.

7. The olfactory sense is closely associated with the early instincts of the wasp.