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Comprehensive Description

provided by Smithsonian Contributions to Zoology
Ammophila atripes Smith

This handsome large species (, 26–31 mm long) belongs to the clavus Group. It has a wide distribution in Sri Lanka though not so wide as A. laevigata Smith, nor is it nearly as common as that taxon. It occurs commonly in the Dry Zone and sparingly in the Wet Zone and ranges from sea level to approximately 650 m in areas receiving average annual rainfall of 965 to 1950 mm. The Ceylonese population belongs to the typical subspecies that Bohart and Menke (1976:151) recorded from mainland Asia; other subspecies occur in Java, Japan, Korea and southern Manchuria, Taiwan, and the Ryukyu Islands. Typical A. atripes is distinguished from the other two species of Ceylonese Ammophila by its larger size ( only 14–20 mm long in A. laevigata and A. basalis Smith), strongly yellowish () or infuscated () wings rather than clear to slightly infumated, and strong transverse ridges on pronotal dorsum, scutum, and propodeal dorsum (present but weak in A. basalis).

COLLECTION LOCATIONS AND DATES.—NORTHERN PROVINCE. Jaffna District: Kilinochchi, 24–27 Jan. Mannar District: Kondachchi, Ma Villu, 11–12 Apr; Marichchukkaddi, 26 Jan; 0.5 mi (0.8 km) NE Kokmotte Bungalow, Wilpattu National Park, 22–23 Jan, 15–16 Feb.

NORTH CENTRAL PROVINCE. Anuradhapura District: Pannika Wila, Wilpattu National Park, 1 Nov; Padaviya, 18–20 May, 20–23 Jul, 11–14 Oct, 28 Nov. Polonnaruwa District: 26 mi (41.6 km) NW Polonnaruwa, 11 Jun.

EASTERN PROVINCE. Trincomalee District: Trincomalee, China Bay Ridge Bungalow, 27–31 Jan, 13–17 May, 24–25 Jul, 8–11 Oct; Kanniyai, 10 Oct. Amparai District: Ekgal Aru Sanctuary Jungle, 19–22 Feb, 9–11 Mar, 9–11 Jun, 11–15 Sep.

CENTRAL PROVINCE. Matale District: Kibissa, 28 Jun–4 Jul; Sigiriya, 18 Jun; 12 mi (19.2 km) S Naula, 14 Jun. Kandy District: Kandy, Udawattakele Sanctuary, 3–5 Jun; Thawalamtenne, 7–8 Sept.

SABARAGAMUWA PROVINCE. Ratnapura District: Uggalkaltota, 23–26 Jun.

UVA PROVINCE. Monaragala District: Angunakolapelessa, 27–28 Mar.

Collecting dates at Padaviya, Trincomalee, and Ekgal Aru suggest that typical A. atripes may breed throughout the year under favorable conditions.

FIELD OBSERVATIONS.—The following account is based on notes 21675 B and C, 5976 A, 52576 C, 61076 C, 12277 C, 21711 A and J, 22077 F, 101077 A, 12179 C, and 31179 A.

One female initiated burrow construction at 1045 on 23 January across the Moderagam Aru near Kokmotte Bungalow in dry sandy soil containing some humus under the baffle of a small Malaise trap, a site mostly exposed to the sun. She flew forward in several directions with the loads of excavated soil, and dropped them 0.7–1.3 m from the burrow entrance. The burrow was at least 80° to the horizontal, and she stopped when she reached a depth of about 2.5 cm. Apparently she must have come upon an obstruction for she began to scratch sand beneath her into the burrow to fill it, and placed a piece of dry leaf over the entrance when the burrow was filled. She then tried to find a new site in the immediate area, scratching soil here and there, and occasionally flying off about a meter to drop a piece of leaf or twig. Apparently a movement of mine frightened her away, for she disappeared and did not return to the site during my periodic visits throughout the day.

We found a small number of females nesting along a shaded path through the jungle at Uggalkaltota on 24–25 June. The four specimens of prey recovered from nests were large, bulky, dark, unpatterned caterpillars, 45–47 mm long, apparently all belonging to the same species of Noctuidae. D.M. Weisman thought that they were nocturnal cutworms or borers because of the dark unpatterned integument. I believe that they were cutworms and that the wasps were hunting for them beneath debris on the ground or in burrows.

P.B. Karunaratne noted the first female (62478 B), 31 mm long, at 1030, 24 June, as she was closing her nest by throwing sand backward beneath her body and into the burrow. Then she grasped a small twig and placed it over the entrance at which time Karunaratne captured her. He was unable to trace the burrow because of the loose soil but he found the paralyzed caterpillar, 4.7 cm long, at a depth of 4.0 cm. The slightly curved wasp egg was 2.8 mm long and 0.9 mm wide, was attached obliquely to the right side of the second abdominal segment, and projected slightly forward.

At 1604 on the same date I found another wasp (62478 C) on this path camouflaging her nest entrance with bits of leaf, rotten wood, twigs, and a lump of mud. She was distributing the debris over a flat area of about 50 cm2. One leaf was 7.5 cm long and some twigs were as long as 10 cm. She worked on the camouflage for 11 minutes before flying off, and I judged from the amount of debris that she had probably worked an equal length of time before I found her. Her paralyzed caterpillar, 4.5 cm long, was beneath 1 cm of loosely packed dirt beneath the debris, and was lying horizontally under dry crumbly soil with interspersed pebbles up to 12 mm in diameter. The egg was 2.5 × 0.9 mm, attached on the right side of the third abdominal segment and projected obliquely backward.

Karunaratne noted a third wasp (62478 D) closing a nest on the same morning. He dug up the nest on the 25th, and found a somewhat shriveled, paralyzed caterpillar of the same species in a horizontal cell at a depth of 5.0 cm. It was being attacked by small ants and the egg was already missing.

At 1015 on 25 June I saw a female A. atripes alight on the woodland path, walk around an area of about a square meter, move a few leaves, and then begin to dig into the earth at an angle of 45°. After a minute and a half she had dug a burrow as deep as the length of her head and thorax. She then came out, scratched some loose soil beneath her into the burrow entrance, made a low orientation flight over the area, and flew off into the undergrowth at 1018. At 1025 a male, 20 mm long, alighted on the ground and crawled around the burrow site, presumably attracted by the scent of the female. I watched this area intermittently for several hours during the day, but the female never returned.

My last series of observations demonstrated that a female of A. atripes will exhume the paralyzed caterpillar on which presumably another female has deposited an egg, feed on that egg, re-inter the caterpillar, lay her own egg on it, and close the burrow. At 1108 on 25 June I observed a female (62578 B) on the same woodland path at the burrow entrance with a large caterpillar that already bore a wasp egg. She appeared to be struggling to get the caterpillar into the burrow. She abandoned this effort, crawled into the burrow and excavated some soil. She flew forward several times, dropping the soil a meter or so from the burrow, and then fed at the side of the caterpillar, undoubtedly on the egg. She reentered the burrow headfirst at 1112, turned around, came to the entrance headfirst, and pulled in the caterpillar whose rear end was still wriggling. She emerged headfirst half a minute later, flew around the area for a few seconds, returned to the entrance, and apparently pushed the caterpillar farther in. Then she brought small lumps of soil, one at a time, placed them singly in the burrow, and pressed them down with her head. Next she scratched loose earth backward beneath her into the burrow, occasionally entering the burrow to compact the soil with her head. She had filled the burrow almost to the surface by 1130, mostly with soil, but she had also incorporated a round seed about 3 mm in diameter and bits of other debris. I did not capture the wasp, and excavated the nest carefully from the side to expose the profile. The nest was in a gentle slope of dry, crumbly, occasionally firm soil. The burrow was 15 mm in diameter, and went downward at an angle of 75°. The entire burrow was plugged solidly, mostly with earthen fill. The caterpillar was lying on its side in a slightly curled position in a horizontal cell 20 mm below the surface. The cell was 30 mm long and 15 mm high. I did not fill the hole I had dug to expose the nest. Microscopic examination of the caterpillar showed the wasp egg of 62578 B attached on the right side of the third abdominal segment. Firmly attached on the following segment was the shriveled egg of the original wasp that had been sucked dry by 62578 B.

At 1430 I noted either 62578 B or another female digging in several places near that burrow site and I captured her. I watched another female from 1500 to 1520 digging in the area containing my excavation of nest 62578 B. Occasionally she palpated with her antennae the cell from which I had removed the caterpillar. This wasp finally flew from the area at 1537 after digging some 2cm below the original cell. I noted a third female elsewhere on the path between 1430 and 1500 digging in several places and then partly filling each short excavation.

The impression I received from these latter observations is that some individuals have adopted a parasitic existence. Clearly, the normal female of A. atripes hunts for its supposedly subterranean prey by smell. Occasionally, however, a wasp must locate a nest containing the paralyzed caterpillar of another wasp instead of a healthy caterpillar. She then digs it up, destroys the egg of the rightful owner, re-inters the caterpillar, deposits her own egg on it, and closes the nest. I should add that later I examined all of the caterpillars obtained from nests of A. atripes and found remains of another egg only on 62578 B.
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bibliographic citation
Krombein, Karl V. 1984. "Biosystematic Studies of Ceylonese Wasps, XII: Behavioral and Life History Notes on Some Sphecidae (Hymenoptera: Sphecoidea)." Smithsonian Contributions to Zoology. 1-30. https://doi.org/10.5479/si.00810282.387