Elasmus

Westwood, 1833

Species Guides

Elasmus polistis

Elasmus is a of chalcid wasps containing over 200 worldwide. It is the sole member of the Elasminae (formerly Elasmidae), though some authorities now place it within Eulophinae. Species are primarily or hyperparasitoids, with documented including lepidopteran larvae and larvae of Polistes paper wasps.

Elasmus by (c) Alan Manson, some rights reserved (CC BY), uploaded by Alan Manson. Used under a CC-BY license.

Elasmus by (c) Katja Schulz, some rights reserved (CC BY), uploaded by Katja Schulz. Used under a CC-BY license.

Elasmus by (c) Justin Williams, some rights reserved (CC BY), uploaded by Justin Williams. Used under a CC-BY license.

Pronunciation

How to pronounce Elasmus: //ˈɛlæs.məs//

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

Images

Habitat

Diverse including rice fields and areas where paper wasp nests occur. In agricultural settings, observed in untreated rice plots of Ciherang variety in Indonesia. Associated with abandoned or active paper wasp nests in residential and natural settings.

Distribution

Worldwide distribution with over 200 . Documented occurrences include: Indonesia (Subang district), USA (Kansas, Missouri, New Jersey, Florida, Indiana, Illinois, Nebraska, Colorado, Arizona, southern California, Hawaii), Canada (Ontario), Mexico, China (Beijing, Hubei), India (Haryana, Kerala), and Russia (Karachay-Cherkess).

Seasonality

In rice agroecosystems, abundance begins late in the growing season, around 70 days after rice planting, with activity increasing toward harvest. In temperate regions, from paper wasp nests has been observed in mid-November and January, suggesting late-season or emergence patterns.

Host Associations

Cnaphalocrosis medinalis - larval Rice leaf folder; rates reached 94.4% near harvest in Indonesia
Polistes metricus - of larvae/pupaePaper wasp; reared from abandoned nests in Kansas and Missouri
Polistes exclamans - Infests young nests when foundress is away foraging

Behavior

In agricultural systems, exhibits late-season buildup with extremely high densities per (up to 225 individuals per larva observed). In paper wasp nest associations, targets (larvae and pupae) and may exploit periods when nest defense is reduced.

Ecological Role

agent in agricultural and natural systems. In rice fields, contributes to suppression of Cnaphalocrosis medinalis with rates exceeding 90% near harvest. In paper wasp , acts as a mortality factor for , potentially influencing colony success.

Human Relevance

Beneficial in rice agriculture due to high rates of leaf folder pests, potentially reducing yield losses. Occasionally encountered by entomologists and naturalists rearing insects from paper wasp nests. No documented negative impacts to humans.

Similar Taxa

DibrachysAlso small reared from paper wasp nests; distinguished by placement (Pteromalidae vs. Eulophidae) and range (Dibrachys has broader host spectrum including hyperparasitism of tachinids and ichneumonids)

More Details

Taxonomic Uncertainty

Classification remains unsettled; treated as sole member of Elasminae by some authorities, but placed in Eulophinae by others. Formerly recognized as distinct Elasmidae.

Hyperparasitism

Some are hyperparasitoids, though specific instances are not detailed in available sources beyond general statements.