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A detailed updated description of the morphology of the larva of Reesa vespulae (Coleoptera: Dermestidae: Megatominae: Megatomini).

The monotypical genus Reesa Beal, 1967 is placed in the tribe Megatomini in the subfamily Megatominae. It is represented by 1 species Reesa vespulae (Milliron, 1939), widely distributed all over the world (Hava 2015). This species was described originally as Perimegatoma vespulae Milliron, 1939 from wasp nests from St. Paul, Minnesota (USA) (Bunalski & Przewozny 2009). Beal (1967) transferred it to a new genus Reesa. According to the results of a phylogenetic analysis based on larval characters, Reesa is closely related to the Trogoderma-like Megatomini (such as Cryptorhopalum Guerin-Meneville, 1838, Megatoma Herbst, 1792, Orphinus Motschulsky, 1858, Thaumaglossa Redtenbacher, 1867, Trogoderma Dejean, 1821) that are characterized by progressive desclerotization of the posterior portions of some abdominal terga (Kiselyova & McHugh 2006). However, Reesa seems to be most similar to Trogoderma and Megatoma. The feature that distinguishes these 3 genera from Cryptorhopalum, Megatoma, Orphinus, and Thaumaglossa is that all hastisetae and hastisetal brushes are inserted on sclerotized areas of terga, never on membranes behind terga (hastisetae are concentrated on the lateral portions of the posterior abdominal terga, behind the row of stout spicisetae). In comparison, in such genera as Cryptorhopalum, Orphinus, and Thaumaglossa, brushes of the hastisetae are inserted on each side of a membrane behind the tergum (Beal 1991; Kiselyova & McHugh 2006).

Larval morphological characteristics that distinguish Reesa from related genera Megatoma and Trogoderma were given by Peacock (1993) and by Beal (1967; 1991), and are mainly expressed by the length of setae of the tarsungulus (pretarsus), the number and morphology of the middle 4 setae of the labro-epipharyngeal margin, and the morphology of the acrotergites.

The current paper provides a detailed morphological description of the mature larva of R. vespulae. The aim of this paper is to update the notes for this species available in the references (see Table 1). The following set of larval characters are described and illustrated: morphology of antenna, epipharynx, mandibles, maxilla, ligula with labial palp, hastisetae, spicisetae, legs, abdominal terga, and condition of antecostal suture.

Materials and Methods

For morphological examination, exuviae or larvae of the last instar were stored in ethanol. The material came from the collection of [dagger]Prof. Maciej Mroczkowski (Warszawa, Poland), Dr. Marek Bunalski (Poznan, Poland), and Dr. Dawid Marczak (Izabelin, Poland). Exuviae were boiled for 3 to 10 min in 10% KOH solution, rinsed with distilled water, and then placed in distilled water for approximately 1 h to clean and soften the material. All structures were mounted in glycerin on slides. The morphological structures were examined under a Nikon Eclipse E 600 phase contrast microscope with a drawing tube attached, and a Nikon SMZ-800 binocular microscope. Photos were taken with Canon 500D and Nikon Coolpix 4500 cameras under Nikon Eclipse 80i and Nikon SMZ-800 miscroscopes.

In addition to the description, plates with drawings of selected structures were prepared for the exuviae. The terminology used in this paper follows Kiselyova & McHugh (2006).

Figure abbreviations: ac--acrotergite; as--antecostal suture (ridge); br--transverse row of placoid sensilla on epipharynx; c--claw; cs--campaniform sensillum; dst--distal epipharyengal sensilla; dmr--dorsomesal row of setae on lacinia; er--epipharyngeal rods; f--femur; gl--galea; l--lacinia; lp--labial palp(i); mp--mesal pair of labro--epipharyngeal setae; msr--mesal row of setae on lacinia; mxp--maxillary palp(i); p2--2nd pair of labro-epipharyngeal setae; pr--pretarsus; pls--placoid sensilla; prst--prostheca; s--sensorium (accessory sensory papillae); sbp--subproximal epipharyngeal sensilla; st--stipes; t--tibia; tr--trochanter.


Subfamily Megatominae Leach, 1815

Tribe Megatomini Leach, 1815

Genus Reesa Beal, 1967

Reesa vespulae (Milliron, 1939) (Figs. 1-19)


Six larvae: [handwritten and unreadable data on the label in the first 2 rows of the text] Erfurt 1969 / Inst. Zool. PAN Warszawa 47/71/Reesa vespulae (Mill.) det. M. Mroczkowski 1971 [ex. coll. Prof. M. Mroczkowski]; 1 ex. of exuviae: Polonia, XV20 Poznan 28.IX.2006 leg. M. Bunalski / Reesa vespulae (Mill.) det. M. Bunalski; many exuviae: Kampinos National Park, Izabelin, Poland, 02.2016, leg. D. Marczak; all specimens deposited in the Department of Invertebrate Biology, Evolution and Conservation, Institute of Environmental Biology, Faculty of Biological Science, University of Wroclaw, Przybyszewskiego 65, Wroclaw, Poland.


Larva, last instar. Length 5.0-6.5 mm. Body fusiform, and relatively long, rather flattened not hunchbacked (Fig. 2). Integument of head, nota, and terga yellowish brown; tergal plates sclerotized (Figs. 1 and 2), sterna hyaline (Fig. 3), femora and tibiae light yellowish (Figs. 1-3). Setae (spicisetae, Fig. 5, and hastisetae, Fig. 6) on tegra and sterna brown (Figs. 1-3). Head protracted and hypognathous (Figs. 2 and 3). Stemmata present on the head. Frons triangular, without frontal, median tubercule. Antennae orientated anterolaterally; composed of 3 antennomeres (Fig. 4). Terminal antennomere 4.0 times as long as wide, with 1 small sensory sensillum (appendage) on apex and 2 campaniform sensilla under half of length of antennomere. Ratio of length of terminal antennomere to length of penultimate and antepenultimate antennomeres combined nearly 0.6:1.0. Sensorium (or sensoria) arising from apex of antennomere 2, in apical position, excavated and slightly extending above apex. Two setae present on antennomere 2 under sensorium. Antennomere 1 with 2-6 long setae and 1-3 campaniform sensilla (cs) (Fig. 4), sensilla are sometimes lacking. Gula separate from postmentum; epicranial stem present. Median endocarina absent. Labro-epipharyngeal margin with 10 or 11 setae in the outer series. Mesal pair (mp) of labro-epipharyngeal setae spatulate (broad) whereas second pair (p2) stout (narrow). On ventral side of epipharynx basal transverse row (br) of placoid sensilla present. Epipharynx with 9 or 10 sensory cups in the proximal transverse series (br), epipharyngeal rods (er) present and diverging proximally. Two sensory cups in the subproximal epipharyngeal sensillum (sbp). Distal epipharyngeal sensilla (dst) arranged in 1 group (enclosed in distinct ring) of 6 (Fig. 9). Lateral setae on epipharynx absent (Fig. 9). Dorsal surface of labroepipharynx with many setae. Mandible brown with dark brown (almost black) apices; apical teeth and ventral accessory process absent. Apical half of mandible heavily sclerotized and sharply delineated from the basal half (Figs. 7 and 8). Mandibular mola and pseudomola absent. Hyaline lobe at ventral base of mandible absent. Prostheca (prst) falciform (Fig. 7), brush of setae absent mesally near the mandibular base. Placoid sensilla (pls) present in approximately one-fourth to one-fifth of the basal dorso-lateral length of mandible (Fig. 8). Maxillary palp composed of 3 palpomeres with terminal palpomere longest. Ratio of terminal palpomere length to the 2 proceeding palpomeres combined 1.0:1.0. First palpomere with 1 seta and 1 campaniform sensillum (sometimes absent), 2nd palpomere with 3 or 4 setae and 1 or 2 campaniform sensilla, and 3rd palpomere with 1 campaniform sensilla and group of 6-8 small sensilla situated in the apical area. Lacinia with 2 heavily sclerotized lacinial teeth, straight at apex. Sclerotization of lacinia separated from stipes. Four straight thick to slender setae present in a dorsomesal row on lacinia (dmr) (Fig. 10). Mesal row of setae on lacinia (msr) composed of 1 basally thickened seta (Fig. 11). Galea arising from stipes terminates close to the apex of lacinia. The apical area of galea covered densely with setae. Stipes with 15-20 long setae placed mainly near the anterolateral margin, 1 short seta present near the inner margin (under the 1st palpomere) (Fig. 12). Hypopharynx hyaline. Bridge sclerite (central part of the distal element of the hypopharyngeal sclerome) appearing jointed medially. Anterior arms of bridge sclerite and distal lateral sclerites of hypopharynx absent. Ligula with 12 lanceolate setae (Fig. 13). Labial palp with 2 palpomeres. First segment wider than 2nd segment; 3.5 times as wide as long, without setae on the disc. Terminal labial palpomere 1.5 times as long as wide, with group of 9 or 10 small sensilla in the apical area and 1 campaniform sensillum (cs) (Fig. 14).

Antecostal suture on notum I absent, but distinct and denticulate on nota II-III and abdominal terga I-IX. Acrotergites of notum I without setae, whereas acrotergites of nota II-III and abdominal terga I-VIII with setae (Figs. 17-19). Notum I with long, stout, large spicisetae along anterior (here directed anteriorly under the head), lateral and posterior margin (here directed latero-posteriorly and vertically upright). These setae on the posterior margin are situated near the latero-posterior angle, some additionally near the suture, and some also present on central area of disc of notum I (Fig. 15). Nota II and III and all abdominal terga with median row of large spicisetae, and along lateral margins of terga (Figs. 17-19). They are mainly directed lateroposteriorly and vertically (upright). Hastisetae of abdominal terga I-VIII forming dense lateral brushes, the longest and thickest on VI-VIII). Setal patterns of abdominal tergum I with numerous large spicisetae in median row; posterior margin bearing only few large spicisetae; hastisetae on median half of the tergite more numerous than spicisetae (Fig. 17). Abdominal tergum VII as illustrated (Fig. 18). Abdominal tergum VIII without pair of abdominal pits (oval apertures); setal patterns as illustrated (Fig. 19). Abdominal tergum IX reduced with numerous long setae. Legs covered with many setae as illustrated (Fig. 16). Claws dark brown. Ratio tibial to femoral length 0.8:1.0. Pretarsus with 2 narrow lanceolate setae inserted at base. Length of posterior pretarsal seta subequal to anterior pretarsal seta (Fig. 16).

Pupa unavailable, but is retained in last larval exuvia, which is interrupted from head to the last abdominal terga (Hong et al. 2014; compare with Fig. 2E, p. 307).


Despite the species' worldwide distribution, there is rather little knowledge about its biology and ecology. As the larvae can cause damage in museum collections and houses, the species has been classified as a pest of collections, households, and food stores. Thus, R. vespulae is also treated as a synanthropic species. The larvae were observed in entomological, bird-skin, dried fungus, or vascular plant collections. They feed on various materials such as dried insects, seeds of tomatoes, dried milk, flour, dried mushrooms, bread crumbs, and food residues. In the USA, the species has been found feeding on dead insects in wasps' nests (Beal 1967; Peacock 1993). It is likely that the species is parthenogenetic (Milliron 1939; Beal 1967). In synanthropic conditions, the larvae can be found throughout the year, but usually from Oct to May. The larvae can survive mild winters in non-heated stores (Bahr 1989; Stejskal & Kucerova 1996). The duration of the development can vary from a few months to 2-3 yr. The adults live from 1 to 2 wk. In Poland, Reesa often co-occurs with other synanthropic skin beetles like Attagenus smirnovi Zhantiev, 1973 (Bunalski & Przewozny 2009).


Due to the fast infestation rate of the species in many European countries (Olafsson 1979; Edwards 1982; Aldini 2003; Hava et al. 2003; O'Connor 2003; Telnov 2008; Bunalski & Przewozny 2009), it is likely that the economic importance of R. vespulae is increasing. Larvae can cause serious damage not only in museum collections (Makisalo 1970; Bahr & Nussbaum 1974; Mehl 1975) but also to other products such as seeds of wheat, rye, tomatoes, dried milk, flour, dried mushrooms, bread crumbs, and dried plant materials (Luff 1982; Peacock 1993; Stejskal & Kucerova 1993, 1996).


Widely distributed in Europe. So far, R. vespulae has also been recorded from Algeria, Egypt, Morocco, Tunisia, Canada, Mexico, the USA, Chile, Afghanistan, China, Japan, Korea, Russia, Australia, and New Zealand (Bunalski & Przewozny 2009; Hong et al. 2014; Hava 2015).


Kiselyova & McHugh (2006) described, compared, and discussed the larval morphology of R. vespulae and evaluated the phylogenetic position of Reesa within Megatominae. However, they found no apomorphic characters in the larvae, but nonetheless retained Reesa within Megatominae as sister to a clade containing such genera as Trogoderma, Thaumaglossa, Megatoma, and Anthrenocerus (see also Hong et al. 2014).

Peacock (1993) wrote that acrotergites are without setae. The results of our study contradict this observation. Acrotergites of abdominal segments possess some very short spicisetae (Figs. 17-19), only the acrotergite of the pronotum is free of setae (Fig. 15). Moreover, tergal color of studied specimens is lighter (yellowish brown to brown) than of those described by Peacock in the key (1993, p. 37: dark brown and strongly pigmented), but this discrepancy may be an expression of variability within the species.


We would like to thank Marek Bunalski (Poznan, Poland) for providing material for this study. We thank Deborah Harvey (RHUL, United Kingdom), Ian Stocks (USA) and Paul Skelley (USA) for commenting on a draft of the manuscript. This study was funded by the Institute of Environmental Biology, Faculty of Biological Science, University of Wroclaw, Poland (project no. 1076/S/IBS/2017).

References Cited

Aldini RN. 2003. Catture con trappole luminose in un'industria di spezie e primo ritrovamento in Italia di Attagenus fasciatus (Thunberg) e Reesa vespulae (Milliron) (Coleoptera Dermestidae). Bollettino di Zoologia Agraria e di Bachicoltura 35: 153-162.

Bahr I. 1989. Uberwinterungsversuche mit einigen Trogoderma-Arten und Reesa vespulae in einer meteorologischen Hutte und einem ungeheizten Gebaude. Mitteilungen aus dem Zentralen Quarantanelaboratorium 1989: 22-25.

Bahr I, Nussbaum P. 1974. Reesa vespulae (Milliron) (Coleoptera: Dermestidae), ein neuer Schadling an Samereien in der Deutschen Demokratischen Republik. Nachrichtenblatt fur den Deutschen Pflanzenschutzdienst 28: 229-231.

Beal RS. 1956. Synopsis of the economic species of Trogoderma occurring in the United States with description of a new species (Coleoptera: Dermestidae). Annals of the Entomological Society of America 49: 559-566.

Beal RS. 1967. A revisionary study of the North American dermestid beetles formerly included in the genus Perimegatoma (Coleoptera). Miscellaneous Publications of Entomologica Americana 5: 281-312.

Beal RS. 1991. Dermestidae (Bostrichoidea) (including Thorictidae, Thylodriidae), pp. 434-439 In Stehr FW [ed.], Immature Insects. Volume 2. Kendall/Hunt, Dubuque, Iowa.

Bunalski M, Przewozny M. 2009. First record of Reesa vespulae (Milliron, 1939) (Coleoptera, Dermestidae), an introduced species of dermestid beetle in Poland. Polskie Pismo Entomologiczne 78: 341-345.

Edwards R. 1982. Notes and observations: Reesa vespulae (Milliron) (Coleoptera, Dermestidae) in Britain. Entomologist's Gazette 33: 34.

Hava J. 2015. World Catalogue of Insects. Volume 13. Dermestidae (Coleoptera). Brill, Leiden/Boston.

Hava J, Zahradnik P, Brutovsky D. 2003. First record of Reesa vespulae (Coleoptera, Dermestidae) in Slovakia. Biologia, Bratislava 58: 240.

Hong K-J, Kim M, Park D-S. 2014. Molecular identification of Reesa vespulae (Milliron) (Coleoptera: Dermestidae), a newly recorded species from Korea. Journal of Asia-Pacific Biodiversity 7: 305-307.

Kiselyova T, McHugh J. 2006. A phylogenetic study of Dermestidae (Coleoptera) based on larval morphology. Systematic Entomology 31: 469-507.

Klausnitzer B. 2001. Die Larven der Kafer Mitteleuropas. Band 6: Polyphaga Teil 5. Spektrum Akademischer Verlag, Berlin/Heidelberg.

Luff ML. 1982. Notes and observations: Reesa vespulae (Milliron) (Col., Dermestidae) infesting stored rye inflorescens near Newcastle. Entomologist's Gazette 33: 40.

Makisalo I. 1970. A new pest of museums in Finland--Reesa vespulae (Mill.) (Coleoptera: Dermestidae). Annales Entomologici Fennici 36: 192-195.

Mehl R. 1975. Amerikansk vepsebolklanner, et skadedyr i museer. Fauna, Oslo 28: 198-204.

Milliron HE. 1939. A parthenogenetic new species of the genus Perimegatoma Horn (Coleoptera: Dermestidae). Annals of the Entomological Society of America 32: 570-574.

O'Connor JP. 2003. Reesa vespulae (Milliron) (Col., Dermestidae) new to Ireland. The Entomologist's Monthly Magazine 139: 12.

Olafsson E. 1979. Hambjalla, Reesa vespulae (Mill.) (Coleoptera, Dermestidae), nytt meindyr a islandi. Natturufraedingurinn 49: 155-162.

Peacock ER. 1993. Adults and larvae of hide, larder and carpet beetles and their relatives (Coleoptera: Dermestidae) and of derodontid beetles (Coleoptera: Derodontidae). Handbooks for the Identification of British Insects 5: 1-144.

Sellenschlo U. 1987. Reesa vespulae und die wichtigsten europaischen Trogoderma-Arten. Bildtafel zur Bestimmung der Larven. Praktische Schadlingsbekampfung 39: 184-185.

Stejskal V, Kucerova Z. 1993. Survey of stored-products pests in rice imported from Vietnam. Ochrana Rostlin 29: 187-191.

Stejskal V, Kucerova Z. 1996. Reesa vespulae (Col., Dermestidae)--a new pest in seed stores in the Czech Republic. Ochrana Rostlin--Plant Protection Science 32: 97-101.

Telnov D. 2008. Species recorded for Latvia after publication of the "Check-list of Latvian beetles (Insecta: Coleoptera)", (last accessed 10 Oct 2016).

Weidner H. 1984. Haus- und Vorratsschadlinge auf dem Vormarsch. 2. Reesa vespulae (Milliron, 1939). DpS--Der praktische Schadlingsbekampfer--Fachzeitschrift fur Schadlingsbekampfung 36: 85-89.

Zhantiev RD. 1976. Zhuki kozheedy fauny SSSR. [The skin eaters family Dermestidae of fauna of the USSR.]. Izdatelstvo Moskovskogo Universiteta, Moskva, Russia.

Marcin Kadej (1,*), Joanna Guziak (1), and Dawid Marczak (2,3)

(1) University of Wroctaw, Faculty of Biological Science, Institute of Environmental Biology, Department of Invertebrate Biology, Evolution and Conservation, Przybyszewskiego 65, PL-51-148 Wroctaw, Poland; E-mail: (M. K.), (J. G.)

(2) University of Ecology and Management in Warsaw, Department of Ecology, Olszewska 12, PL-00-792 Warsaw, Poland

(3) Kampinos National Park, Tetmajera 38, PL-05-080 Izabelin, Poland; E-mail: (D. M.)

(*) Corresponding author; E-mail: (M. K.)

Caption: Figs. 1-3. Mature larva of Reesa vespulae (Milliron): 1, dorsal view; 2, lateral view; 3, ventral view. Scale bar = 1.0 mm.

Caption: Figs. 4-14. Mature larva of Reesa vespulae (Milliron): 4, antenna (dorso-fronto-lateral); 5, spiciseta; 6, hastiseta; 7, right mandible (dorsal); 8, mandible (latero-ventral); 9, epipharynx (ventral); 10, lacinia (dorsal); 11, lacinia (ventral); 12, maxilla (ventral); 13, labium (ventral); 14, labial palp (ventral). Scale bar = 0.1 mm.

Caption: Figs. 15-19. Mature larva of Reesa vespulae (Milliron): 15, pronotum (dorsal, right half; large circles represent points of insertion of large spicisetae, small circles represent points of insertion of hastisetae); 16, right foreleg (dorsal); 17, abdominal tergum I (dorsal, right half; large circles represent points of insertion of large spicisetae, small circles represent points of insertion of hastisetae); 18, abdominal tergum VII (dorsal, right half); 19, abdominal tergum VIII (dorsal, right half). Scale bar = 0.1 mm.

Please Note: Illustration(s) are not available due to copyright restrictions.
Table 1. List of references to larval morphological characteristics of
Reesa vespulae (Milliron, 1939).

Reference                  Available data

Milliron 1939              Short description of
                           larval morphology (p. 572)
Beal 1956                  Short sentence
                           in key (p. 561)
Beal 1967                  Short sentence in
                           key (p. 290),
                           brief description
                           of larval morphology (p. 310)
Zhantiev 1976              Short sentence in
                           key (p. 94) [in Russian]
Weidner 1984               Illustration of
                           larva (p. 88)
Sellenschlo 1987           Short description in
                           key (p. 124), illustration
                           of antenna (p. 123),
                           papillae of epipharynx (p. 124)
Beal 1991                  Short sentence in key (p. 439)
Peacock 1993               Short description in
                           key (p. 37), illustration
                           of pretarsus (p. 123),
                           epipharynx (p. 126),
                           antenna (p. 138),
                           abdominal tergite I (p. 139)
Stejskal & Kucerova 1996   Picture of dorsal aspect
                           of larva (p. 98), pretarsal
                           claw (p. 99), abdominal
                           hastisetae (p. 99)
Klausnitzer 2001           Short description in key
                           (p. 33-34) [in German],
                           illustration of antenna
                           (p. 30), pretarsus (p. 30),
                           epipharynx (p. 30),
                           abdominal segment I (p. 30)
Kiselyova & McHugh 2006    Data matrix with
                           larval characters (p. 498)
Hong et al. 2014           Illustration of larva
                           (dorsal and ventral
                           view, p. 307) and
                           pupa in last larval
                           exuvia (dorsal view,
                           p. 307)
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Author:Kadej, Marcin; Guziak, Joanna; Marczak, Dawid
Publication:Florida Entomologist
Article Type:Report
Date:Jun 1, 2017
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