Myrmeleon bore (Tjeder, 1941)

Zhang, Jie, Zhang, Xubo & Wang, Xinli, 2013, Larvae of Cueta sauteri (Esben-Petersen) and Myrmeleon bore (Tjeder) (Neuroptera, Myrmeleontidae): description and behavioral notes, Zootaxa 3734 (3), pp. 362-370 : 365-367

Myrmeleon bore (Tjeder, 1941) (Figs. 3, 4)

Size: body length (including mandibles) 14.5–15.0 mm, body width (widest part) 4.8–5.0 mm, head length (without mandibles) 2.0–2.1 mm, head width (widest part) 1.8–1.9 mm, length of the mandibles 2.5–2.6 mm.

Head: dark brown from dorsal view and yellow brown from ventral view. Head capsule is approximately oval with numerous bristles. Two pairs of oblique dark stripes on posterior part and 3 black spots near anterior margin from dorsal view (Fig. 8); ventral side of head capsule with two dark brown stripes near each other anteriorly and far separated posteriorly (Fig. 9). Mandible yellowish brown and dark brown at apex. Mandibular teeth yellowish brown with dark brown apex. Mandibular length longer than head capsule length, with three teeth; tooth 3 longer than 2; all teeth usually equidistant; 1–2 bristles between the third tooth and apex of mandible, 2–3 bristles between tooth 2 and 3; the longest setae on exterior margin of mandible longer than mandibular greatest width (Fig. 10). Antennae filiform, long and slender ( Fig. 13 ). Ocular tubercle black, consisiting of 7 dark stemmata ( Figs. 13, 14 ). Some bristles are among stemmata. Labial palpi shorter than basal width of mandible, three segments, the third segment darker ( Fig. 12 ).

Thorax: trapezoid, prothorax is the narrowest segment. Tergites dark brown with scarce dark spots and numerous bristles, sternum yellow brown (Fig. 22). Each notum with a pair of punctums; lateral scoli welldeveloped with tufts of bristles; mesothoracic spiracle no enlongated peduncles (Figs. 18, 22).

Abdomen: 10-segmented, the 10th segment invaginated. Tergites dark brown with black spots and sternum yellow brown with some black spots and simply tubercles (Figs. 3, 4); sternite VIII with a pair of inconspicuous yellow teeth at posterior margin (Fig. 23); sternite IX with two rows of lateral long bristles (anterior row 6, posterior row 6), oblate digging bristles in 3 rows (2, 4, 8) (Figs. 23, 24).

Examined material. 5 larvae, Beidaihe, Qinhuangdao, Hebei Province, China (39° 49’ N, 119° 28’ E), 19. VII. 2008, Xu-Bo Zhang (CAU0041–CAU0045). All the specimens were deposited in ICCAU.

Larvae of Cueta sauteri and Myrmeleon bore are capable of constructing similar conical pitfall traps in loose soil and sand, and then wait for preys at the bottom of the traps. In the laboratory, we observed that the larvae of these two species only move backwards on sand surface.

The digging activity of C. sauteri larvae includes three stages. During the first stage, the larva backs into the sand and stays still for a period of time. In the second stage, the larva moves around randomly (backwards) just beneath the sand surface, and then selects an appropriate location and excavates the initial circular furrow of the pit. In the third stage, the larva moves backward to the center with spiral movements in a clockwise or counterclockwise direction and then the funnel traps are finished. These backward movements are accompanied by a sandtossing behavior of the head and mandibles. Just before the pupation occurs, the third instar larvae of C. sauteri no longer build funnel-shaped pits. The larvae crawl around in the sand and then make a cocoon. Pupation occurs in a cocoon made of silk and tiny particles of soil.

The pitbuilding behavior and pupation of Cueta sauteri is similar to that of Myrmeleon bore reported by Gepp et al. (1989). But when the larvae of M. bore are waiting for a prey at the bottom of the trap, the body is covered with sand as the mandible and a portion of the head are exposed. Sometimes, the mandible and the entire head capsule are exposed to the outside environment.

Figures

FIGURES 11, 15 – 17. Third instar larva of Cueta sauteri. 11. Labial palpi. 15. Antennae and ocular tubercle (dorsal view). 16. Ocular tubercle (ventral view). 17. Mesothoracic spiracles. FIGURES 12 – 14, 18. Third instar larva of Myrmeleon bore. 12. Labial palpi. 13. Antennae and ocular tubercle (dorsal view). 14. Ocular tubercle (ventral view). 18. Mesothoracic spiracles.