G. B. Fairchild.
A Note on the Early Stages of Lepiselaga crassipes Fab. (Diptera, Tabanidae).
Psyche 47(1):8-13, 1940.

This article at Hindawi Publishing: https://doi.org/10.1155/1940/57946
CEC's scan of this article: http://psyche.entclub.org/pdf/47/47-008.pdf, 536K
This landing page: http://psyche.entclub.org/47/47-008.html

The following unprocessed text is extracted automatically from the PDF file, and is likely to be both incomplete and full of errors. Please consult the PDF file for the complete article.

Psyche
[March
A NOTE ON THE EARLY STAGES OF
LEPISELAGA CRASSIPES FAB.
(DIPT., TABANIDZ)
Junior Entomologist,
Gorgas Memorial Laboratory,
Panama, R. de P.
Information about the early stages of Neotropical Tabani- dse may almost be said to be non-existent. Bodkin and
Cleare (1916) have given a brief description of the larvae and a figure of the pupal aster of Tabanus desertus Wlk. Ad. Lutz (1920, 1922 and 1928) has mentioned raising a few species from larvse, and has described a method of rearing using agar as a medium (1920), but so far as I am aware these are the only descriptions or figures of larvse or pupae of any of the many Neotropical forms that have ever been published.
Inasmuch as the classification of the Tabanidse, so far based entirely on adult characters, is in a very unsatisfac- tory condition, I feel that any information about the struc- ture and habits of the early stages is very important, and may throw some much needed light on the relationships of the many forms.
The present species has apparently been reared more often than any other, and has been mentioned several times in the literature. Ad. Lutz (1928) raised a single adult from a larva collected in plants of Pistia stratiotes, the water lettuce, in Venezuela, and gives an unrecognizable figure of the pupal shell. Dunn (1934) also raised the adults from larvas taken in the same habitat in Panama, but says nothing about the appearance of either larva or pupa.
During the early months of 1929, while searching for mosquito larvae in the floating vegetation along the Chagres Pachc 4FB-11 IIC-tO). http llpsychr enlclub.mg/47/47-008 hlml



================================================================================

19401 Early Stages of Lepiselaga crassipes 9 River between Gamboa and Madden Dam in the Panama Canal Zone, I occasionally dipped up small pupal shells of what I suspected might be Lepiselaga,. Comparison of these with a specimen in our collection from which Dunn had bred Lepiselaga confirmed my suspicion.
Although, for reasons which are not known, Pistia has become very scarce throughout the Canal Zone this year, I have taken the adult Lepiselaga in fair numbers throughout the year. I auspect, therefore, that it is not entirely de- pendent on this plant, but may be associated with other types of aquatic vegetation as well. In April 1939, while collecting in a small slough near the laboratory's station at Juan Mina on the Chagres River, I secured two small green- ish larvae from the matted floating vegetation near the shore line. This v&getation consisted of floating debris, mats of filamentous algee, the water-fern SaIvink, and a few small plants of Pistia, not over 1.5 inches in diameter. The larvae were associated with a rather rich fauna of aquatic insects, including larvae of Odonota, Ephemerida and Stratb mgiidge, and numerous species of aquatic Coleoytera and Hemiytera. At the same time I also took two pupal shells. Later, in mid-May of the same year, I collected two more larvse of Lepiselaga in a grassy awamp near Gamboa. They were in the floating scum on the water, and no Pistia was present in the swamp.
The first two larvae were kept in the laboratory in shell vials measuring 3 x 1 inches, into which about 1 inch of 2% agar had been poured. This medium remains more or less transparent for one or two weeks, when the larvse may be removed to a new tube if it is desired to keep them under close observation. Inoculation of the medium with some unicellular green alga seems to keep the medium from be- coming putrid for a longer time, but the dark green color interferes with observation.
To provide a suitable place for
pupation, paper towelling is cut into strips 1.5 inches wide and 3 or 4 inch- long, rolled into a cylinder the size of a lead pencil, moistened and inserted upright into the agar. The tubes are stoppered tightly with cotton, which must not touch the roll of paper, or it will suck all excess moisture from the paper and agar.
The larvae may be fed upon
aquatic earthworms, Chironomid larvae or other amall so-ft-



================================================================================

10 Psyche . [March
bodied forms, but I have found the most satisfactory food to be ordinary earthworms. A culture of these may be kept in the laboratory for long periods, and one fair-sized worm cut in pieces will feed ten or a dozen larv~. After about 3 weeks in the laboratory, during which they both fed several times, one of these larvae pupated, yielding a pupa which resembled the empty pupal shells I had previously found. The other was hastily preserved for study. I was obliged to leave the laboratory for five days after this, and when I returned, found that a male Lepiselaga had emerged in my absence, so that the pupal period is not more than a week and probably 4 or 5 days. The full-grown larva is about 15 mm. long by 3-3.5 mm. wide at the widest part in the region of the 5th or 6th seg- ment, circular in cross-section, or sometimes slightly flat- tened ventrally. In color it is a light yellowish green with a complicated dorsal pattern of dark grey spots and blotches on the second to tenth segments. Laterally there are two short parallel longitudinal dark lines of spots ; below there is a dark spot on each of the second to 10th segments. The ventral surface is unmarked, as are the first and last seg- ments. Both the head and siphon are unusually slender, and the anterior part of the body has great powers of extension, so that when extended in crawling the head and first two segments may make up % of the total length. The loco- motory protuberances include a narrow transverse dorsal pair, a rounded lateral protuberance on each side, and an oval ventral pair. Thus each segment from the 6th to the 10th inclusive bears 6 protuberances. The 5th segment lacks the ventral pair, and the dorsal pair are narrowed. These protuberances are extensile to some extent and bear dense short hairs. There are also a few long hairs in the head and anal regions, and at least a lateral pair on each segment, which are difficult to see. The anal region is less swollen than in other Tabanid larvae I have seen, and does not appear to be used so much in locomotion. The 'apical part of the siphon is rather heavily chitinized and longitudinally striated, and bears near its apex four groups of three hairs each. The opening at the apex is a vertical slit fringed with minute hairs. In this slit, and lying between the ends of the two big tracheal trunks, is a heavily chitinized spear-



================================================================================

19401 Early Stages of Lepiselaga crassipes 11 like structure which seems to be capable of considerable extrusion and retraction. Hart (1895) mentions this struc- ture as being present in all the Tabanid larvae he examined, but noted that it was retractile, so that in many specimens it was not visible. He gives a figure of it in lateral view for Tabanus nigrescers. Stone (1930) also mentions this structure and uses it in his key, it being found in some spe- cies of Chrysops and Tabanus but not in others. Such a structure would seem quite well adapted to piercing the air spaces in the roots and leaves of such aquatic plants as Pistia and Piaropw, while allowing the larva to secure air from the water surface when such plants are not available. In any case, the larvae live quite well under artificial con- ditions, apparently not needing aquatic vegetation from which to secure air.
The pupa is 10-14 mm. long, the abdomen relatively short, for the head and thoracic region are only slightly less than half the total length of the pupa. The head-capsule is smooth and rounded, lacking the bosses and rugosities often found in other species of the family.
The thoracic spiracles
are produced into relatively long conical trumpets, which are directed sidewise with their openings on the ventral side of the apex. These elongated thoracic trumpets have been found in only one other Tabanid, so far as I am aware. King (1926) records similar structures for 'Tabanus fascia- tus niloticus Aust., a species which he found breeding in Pistia on the Nile. The 1st. to 4th. free abdominal segments bear long spines where the spiracles should occur. These at first sight appear to be breathing-tubes, but I cannot find that they are open at the apex. Each abdominal segment in addition bears a row of fine spines of variable length near its posterior margin, which are longer on the dorsal side. The female aster is shown in Fig. 5. The male aster is narrower, the lateral spines are relatively longer, and the ventral region of the last segment is considerably inflated. In color the pupa is light leaf green, becoming nearly black before emergence, when the colors of the adult can be clearly seen through the integument.




================================================================================

'EXPLANATION OF PLATE 11.
[March
Fig. 1.
Dorsal view of full grown larva of Lepiselaga a'assipes, show- ing distribution of locomotory protuberances. Color markings omitted.
Fig. 2.
Dorsal view of 7th segment, showing color pattern. Fig. 3. Dorsal view of Siphon. a. tracheal trunks. b. apical slit. c. siphonal spear.
Fig. 4.
Lateral view of 8 pupa.
Fig. 5.
Terminal view of last segment and aster of $ pupa. REFERENCES.
Hart, C. A. On the Entomology of the Illinois River ancl Adjacent Waters. First Paper. Bull. Illinois State Lab. Nat. Hist. IV, Article Vi. p. 222, pi. XI, Fig. 48.
Urbaiia, Illinois. 1895.
Bodkin, G. E. and Cleare, L. D., Jr. Notes on some animal para- sites in British Guiana.
Bull. Ent. Res., VII, p. 184, Fig. 1, 1916. Ad. Lutz, Obervac5o de vermes e larvas terrestres ou limicolas em anlbiente transparente. Folha Medica, Anno. 1, No. 3, March 1920 ( Separate).
Ad. Lutz, Zoologia Medica. Folha Medica, p. 89. ( Separate). King, H. H. A note on the bionomics of Tnhcm~s fasciatus niloticus Aust. Bull. E'nt. Res., 16, p. 359, March 1926. Ad. Lutz, Estudios de Zoologia y Parasitologia Yenezolanos, Rio de Janeiro, pp. 59-60, pi. 3, fig. 7, Dec., 3938. Stone, Alan. The Bionomics of some Tabanidae (Diptera) Ann. Ent. Soc. Amer. XXIII, 2, pp. 261-304, Figs. 1-12, June 1930. Dunn, L. H. Notes on the water lettuce, Pistia stratiotes, as a
nursery of insect life. Ecologv, XV, No. 3, 111). 329-333, July 1934.



================================================================================

19401 Early Stages of Lepiselaga crassipes 13 Psyche, 1940
VOL. 47, PLATE 11.
Fairchild - LepLselagu crussipes




================================================================================