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1955
The Lepidopterists' Netvs
55
DISTRIBUTION OF THE MOTH EAR MITE (MYRMONYSSUS PHAL/ENODECTES)
by Asher E. Treat
For the three years since its discovery in Tyringham, Massachusetts, the gamasine mite Myrmonyssus phalcenodectes Treat, a parasite in the tympanic organs of noctuid moths, has been known only from the type locality and from Bergen County, New Jersey. The wide variety of hosts, however, and the high incidence of infestation in some species made it seem probable that the mite was more widely distributed, and that it could be found in museum collections of Lepidoptera. Through the kindness of Dr. F. H. RiNDGE of the American Museum of Natural History, Dr. J. G. Franclemont and Dr. W. T. M. Forbes of Cornell University, and Dr. E. L. Todd of the United States National Museum, permission was obtained to examine the specimens of Pseudaletia, Leucania, and related genera in those institutions. This paper presents evidence that the range of the mite is nearly worldwide.
The description of the mite, together with notes on its biology and ecology, has recently appeared elsewhere (Treat, 1954). Among known parasites of adult Lepidoptera, M. phalcenodectes is unusual if not unique in that at least during the warmer parts of the year it lays its eggs and completes its life cycle entirely upon or within the body of its host. It has thus far been reported only from adult noctuid moths, chiefly those of the genera named above, though several others are occasionally infested. Colonies of the mites develop unilaterally in the tympanic air sac and associated cavities, destroying the auditory function of these parts but sparing the corresponding structures of the opposite side. Since the tympanic organs are generally acknowledged to be at least partly auditory in character (Schaller & Timm, 1950; Treat, in press), it seems appropriate to use the name Moth Ear Mite for this parasite, despite the obvious lack of homology between the tympanic organ and a vertebrate ear. The usage may gain some authority from the opinion of Imms (1947) that "These [tympanic] organs may with some justice be regarded as ears."
Evidence of infestation is easily detected even in pinned specimens, provided that the wings have been properly spread and that the legs do not conceal the external tympanic recess. If the mite colony was moderately or well advanced when the moth was captured, slight displacement of the setae with a fine needle under the binocular microscope will usually reveal either the mites or their eggs. The dried mites are yellowish brown and much flattened. To the casual glance they might be mistaken for dermestid feces. The eggs, when dry, are shrivelled and yellowish. They are usually attached to the conjunctiva ("accessory" or "false" tympanal membrane of Richards, 1933, and other authors), which may also be pitted and discolored by older egg scars. Although the eggs are not distinctive as compared with those of other mites of similar size, their presence together with rupture or perforation of the
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Treat: Moth ear mite
Vol.9: nos.2-3
tympanic membrane may be taken as tentatively diagnostic for the Moth Ear Mite. If the pinned specimen can be dissected to the extent of removal of the first abdominal tergite on the side of the suspected infestation, the mites can usually be found in the tympanic air sac or countertympanic cavity. Mites and eggs, either fresh or dried, may be mounted directly in Hoyer's medium (Baker & Wharton, 1952). They can be cleared and relaxed by gentle heating of the slide after the coverslip has been placed.
The table includes records from all of the chief biogeographical regions, obtained from the study of specimens chiefly of Leucania and related genera in the three collections mentioned above. In the American Museum, Nearctic as well as exotic material was examined. In the other two collections, only exotic forms were studied, and in the U. S. National Museum the investigation was limited to Palearctic, African, Oriental, and Hawaiian specimens. Host names are given as they appear in the various collections. The scarcity of Palearctic records may perhaps be explained by the comparatively small amount of material available for study.
Seasonal distribution follows the expected pattern, with the highest incidence for the temperate regions of both northern and southern hemispheres in midsummer, and with scattered records in the tropics throughout the year. In northeastern New Jersey, infested moths have been taken as early as June 9 and as late as October 23- The winter quarters of the mite remain to be discovered. The present data increase the number of recorded host species from 23 to 48.
Records of Myrmonyssus phalcenodectes from Specimens Chiefly of Leucania and Related Genera in the American Museum of Natural History [AMNH], Cornell University [CU], and the United States National Museum [USNMJ.
Locality
Date
Host Species
NEARCTIC Rangeley, Me. Cohasset, Mass. Cohasset, Mass. Dorchester, Mass. New Windsor, N.Y. New Rochelle, N.Y. Mendham, N.J. Mendham, N.J. Dumont, NJ. Chester, N.J. Newark, NJ. Pennsylvania Washington, D.C. Iowa City, Iowa Volga, S.Dak. Ft. William, Ont. near Hattiesburg, Miss. New Orleans, La.
24 Aug. 1949
19 July 3 Sept.
10 July 1901 9 July 1891 24 Aug. 1949
20 Aug. 1935 29 Aug. 1952 23 Oct. 1954 17 Aug.
16 Aug. 1882 4 Aug. 1898
15 Aug. 1953 1-11 Oct. 1944 4 Oct. 1951
Pseudaletia unipuncta Haw. [AMNH]
Leucania i. insueta Gn. [AMNH]
$cotogramma t. trifolii Rott. [AMNH]
Leucania commoides Gn. [AMNH]
L. pseudargyria Gn. [AMNH] *
Pseudaletia unipuncta Haw. [AMNH]
L. phragmatidicola Gn. [AMNH]*
L. multilinea Wlk. [AMNH]*
Sunira bicolorago Gn. [author's coll.]
L. multilinea Wlk. [AMNH]
L. extincta flabilis Grt. [AMNH]
L. pseudargyria Gn. [AMNH]
L. scirpicola Gn. [AMNH]
L. phragmatidicola Gn. [AMNH]
Aletia o. oxygala Grt. [AMNH]
A. oxygala luteopallens Smith [AMNH]
L. e. extincta Gn. [AMNH]
L. linita Gn. [AMNH]
1955
The Lepidopterists' Neivs
57
Locality
Date
Host Species
Lake Okechobee, Fla. Harris County, Texas near Forestburg, Texas Wichita Falls, Texas Minnehaha, Yavapai
Co., Ariz. Malibu, Calif. Rancho La Sierra, Riverside Co., Calif. Berkeley, Calif. San Mateo, Calif.
NEOTROPICAL Jalapa, Mexico Punta Prieta, Baja Cal.,
Mexico El Volcano, Chiriqui,
Panama Jamaica, Br. W. Indies Cabanas, Cuba Moengo, Surinam Pelotas, Brazil La Estanzuela, Uruguay La Estanzuela, Uruguay
ETHIOPIAN
Umtali, Southern Rhod. Umtali, Southern Rhod.
ORIENTAL
Tjibodas, Mt. Gede, Java Mt. Makiling, Luzon,
P.L Arisan, Formosa Suisha, Formosa
PALEARCTIC
Yachow, China near Mupin, China
AUSTRALASIAN Ninay Valley, Dutch
New Guinea Victoria, Australia
OCEANIC
Kauai, Hawaii
30 April 1912 Leucania sp. Leucania sp. 24 Sept. 1950 7 Oct. 1950 4 Oct.
(undet.) [AMNHj (undet.) [AMNH] L. phragmatidicola Gn. [AMNH] L. phragmatidicola Gn. [AMNH] L. imperfecta Smith [AMNH]
10 Aug. 1941 L. oaxacana Schaus [AMNH]
23 Sept. 1940 L. oaxacana Schaus [AMNH]
3 Sept. 1941 L. oregona Smith [AMNH]
14 Sept. 1941 L. oregona Smith [AMNH]
Pseudaletia sequax Francl. [AMNH] 27 March 1935 Trichoclea e. edwardsi Smith [AMNH]
3 March 1936 P. unipuncta antica Wlk. [AMNH]
1953
5-8 Sept. 1913 17 May 1927 27 Aug. 1951 Jan. 1953 7 Jan. 1953
15 Aug.
P. sequax Francl. [AMNH] P. sequax Francl. [AMNH] Cirphis humidicola Gn. [CU] P. sequax Francl. [CU] P. adult era Schaus [CU]t Cirphis (= Faronta) albilinea Hiibner [CU]
Borolia micropis Hampson [CU] * Borolia torrentium Gn. [CU]*
Cirphis lasiomera Hampson [USNM] Borolia aspersa Snell [USNM]
3 June 1932 Cirphis albicosta Moore LCU] 1 June 1934 C. albicosta Moore [CU]
Cirphis sinuosa Moore [USNM] * Leucania sp. (undet.) [USNM]
Nov. 1908 to Cirphis leucosphenia Bethune-Baker Jan. 1909 [CU|
Pseudaletia australis Francl. [AMNH]
May
Cirphis amblycasis Meyr. [USNM]
* Diagnosis of Aiyrmonyssus phalcenodectes made from eggs and host damage only. tlncidence of infestation 54 percent (82 out of 152 specimens).
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TREAT: Moth ear mite
Vol.9: nos.2-3
References
Baker, E. W., & G. W. Wharton, 1952. An introduction to acarology: p. 10. The
Macmillan Co., N. Y. Imms, A. D., 1947. Insect natural history, p. 83. Collins, London. Richards, A. G., 1933. Comparative skeletal morphology of the noctuid tympanum.
Ent. A?nericana 13 (n. s.): 1-44. Schaller, F., & C. Timm, 1950. Das Horvermogen der Nachtschmetterlinge. Zeitschr.
vergl. Physiol. 32: 468-481. Treat, A. E., 1954. A new gamasid (Acarina: Mesostigmata) inhabiting the tympanic
organs of phalaenid moths. Journ. Parasitol. 40: 619-631. Treat, A. E. The response to sound in certain Lepidoptera. Ann. Ent. Soc. Amer.
In press.
Dept. of Biology, The City College of New York, New York 31, N. Y., U.S.A.
AN APPARATUS FOR WEIGHING SMALL INSECTS by P. H. H. Gray
The writer recently presented (1953) a short article pointing out the existence of correlations between the wing-radii and the weights of certain butterflies. Since weighing small butterflies such as Pieris rupee L. on a beam balance is tedious, the apparatus described below was devised whereby each insect can be weighed in a few seconds. The apparatus is shown diagrammati-cally in the figure, at the scale of l/i inch to 1 inch.
Two separate wooden blocks form the framework of the apparatus; they are free to be moved for slight adjustments in distance or angle. A length of wire was removed from copper window-screening. The wire is about 15 inches long, half of it forming the balance wire and the remainder being coiled in a loop behind the fulcrum point shown on the left-hand block in the diagram. At the free end the wire was twisted through a right-angle and coiled in a small loop, as in the first stage of making a simple knot. The loop is about one-half of an inch is diameter, with the ultimate two or three bends serving as the pointer.