Melolonthinae

MacLeay, 1819

June Beetles, June bugs, cockchafers, May beetles

Tribe Guides

is a large and diverse of scarab beetles (Scarabaeidae) containing over 11,000 in more than 750 , distributed worldwide. range from 3 to 58 mm in length and are typically brown or black, often with setae or . The subfamily includes economically important pests such as the Melolontha cockchafers and Phyllophaga May beetles, whose larvae feed on plant roots while adults feed on foliage or may be non-feeding. Many species exhibit pronounced in , with males bearing large antennae to detect female .

Amphimallon by (c) Thierry Arbault, some rights reserved (CC BY), uploaded by Thierry Arbault. Used under a CC-BY license.

Macrodactylus subspinosus by (c) christine123, some rights reserved (CC BY), uploaded by christine123. Used under a CC-BY license.

Amblonoxia harfordi by no rights reserved, uploaded by Adam Wachtel. Used under a CC0 license.

Pronunciation

How to pronounce Melolonthinae: /ˌmɛloʊˈlɒnθɪniː/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from other scarab by combination of: unarmed (no teeth); exposed scutellum at base of ; straight elytral margins; antennal bases concealed from above; and particularly pronounced in antennal size and structure. Larvae identified by Y-shaped or angulate anal cleft, or tightly fitting and , and lacking stridulatory areas. Separated from Rutelinae by less brilliant coloration and specific antennal and mouthpart characters; from Dynastinae by lack of prominent horns and smaller size; from Cetoniinae by exposed scutellum and straight elytral margins.

Images

Habitat

occur above ground in diverse terrestrial including forests, grasslands, agricultural areas, and sand dunes. Larvae develop in soil, feeding on roots and humus. Some are restricted to specific habitats such as sand dunes (e.g., many Polyphylla species).

Distribution

Worldwide distribution across most terrestrial regions. Particularly diverse in temperate and tropical zones. Contains regionally and , such as Pacuvia and Lichniini in Chile, Holotrichia in India, and numerous genera in the southwestern United States.

Seasonality

activity varies by and region. Many temperate species (e.g., Melolontha, Phyllophaga, Polyphylla) emerge in late spring to early summer, giving rise to "June beetles" or "May beetles." Adults of some species are or , active shortly after sunset with limited activity windows of hours to weeks. Some flower-feeding species are .

Diet

Larvae feed on plant roots and humus; recorded plants include grasses, clover, and sugarcane. feeding habits vary: some feed on leaves of trees (including eucalypts), flowers, or pollen (e.g., Automolius, Diphucephala, Heteronyx, Liparetrus, Phyllotocus, Sericesthis), while others are non-feeding (e.g., Antitrogus, Rhopaea).

Life Cycle

Complete with four stages: , larva, pupa, and . Eggs laid in soil; larval and pupal stages occur in soil. Larval stage is prolonged, lasting up to two years in some . Adult stage is short, typically lasting only days to weeks. Larvae pass through three instars before .

Behavior

are primarily or , often attracted to light. Flower- and pollen-feeding may be . Males use enlarged to detect female ; in non-feeding species, virgin females emit to attract males, while in feeding species adults aggregate on plants to locate mates. Some species exhibit swarming . Males of some sand-dwelling species (e.g., Polyphylla) fly rapidly upwind in zig-zag patterns to locate females.

Ecological Role

Larvae function as soil-dwelling herbivores and , processing organic matter and affecting plant root systems. serve as folivores, florivores, or where feeding occurs. Some are significant agricultural pests. Larvae may be prey for soil-dwelling and , including Pyrgota flies (endoparasitoids).

Human Relevance

Economically significant as agricultural and forestry pests. Larvae of Sericesthis damage pastures; larvae of Dermolepida albohirtum, Antitrogus, and Lepidiota attack sugarcane; Lepidiota stigma also damages corn, sorghum, and fruits. of Phyllophaga species can cause complete defoliation of deciduous trees. Some species feature in folklore due to their size and swarming (e.g., Melolontha cockchafers). Attracted to artificial lights, sometimes causing nuisance. Used as bioindicators and studied for .

Similar Taxa

RutelinaeSimilar plesiomorphic body form, but distinguished by often more brilliant or iridescent coloration and different mouthpart and antennal characters.
DynastinaeSome smaller dynastines (e.g., Cyclocephala) resemble melolonthines, but Dynastinae typically have horns or on /pronotum in males and different antennal structure.
CetoniinaeSimilar general scarab form, but Cetoniinae usually have scutellum covered by and often more convex body shape.
SericinaeFormerly included within , now separated based on phylogenetic studies; difficult to distinguish without detailed examination.

More Details

Systematic History

Recent phylogenetic studies have shown that the traditional broad concept of was . To resolve this, Sericinae and Sericoidinae have been reinstated as separate lineages. The subfamily now contains approximately 30 recognized tribes, though classification remains in flux with new tribes described as recently as 2021.

Sexual Communication

The pronounced antennal dimorphism reflects different mating strategies: in feeding , aggregate on plants using both visual and olfactory cues; in non-feeding species, females remain in soil or concealed locations and emit long-range detected by males using their enlarged . This dichotomy represents a major behavioral divide within the .

Flightlessness

Flightlessness has evolved in some , particularly females of certain lineages. Female Pacuvia philippiana exhibits brachyptery, and many female Polyphylla in sand dune are flightless, remaining buried in sand while males fly to locate them.