Apidae > Melissodes > Melissodes trinodis / Melissodes agilis

If you grow sunflowers in your backyard garden, you won’t have to go very far to find one of this pair of longhorn bees Melissodes trinodis and Melissodes agilis. Separating this species pair in the field is difficult (especially males), and both members have a strong preference for foraging on sunflowers and similar Asteraceae. At night, males can be found sleeping on sunflower heads at the junction between the ray and disc florets, sometimes in groups of a dozen or more individuals.

Phenology

Summer, June through August, with some records into September if sunflower host plants are available.

Range

Widespread throughout region, especially in areas with cultivated sunflowers. M. trinodis females seem to be encountered most often in the northeast, whereas M. agilis females seem to be encountered more often further west.

Appearance

Size << honey bee

Females have short antennae, bluish eyes, rich orange thorax hairs, and crisp abdominal banding. Females are often seen carrying enormous bundles of yellow aster pollen in their hind scopae.

Males are smaller than females, with very long antennae, green eyes, variable thorax hairs ranging from gray-yellow to orange, and diffuse banding on the abdomen.

Similar species

• Female Melissodes trinodis tends to have distinct thin white abdominal bands, whereas female M. agilis have thicker, appressed bands of white hair (especially lower on the abdomen).
• We do not know males of M. trinodis and M. agilis to be reliably distinguishable in the field.
• M. subilllatus also occurs on composite Asteraceae early in the season, but tends to have slightly earlier phenology and females are noticeably gray in color with blackish thorax. Although M. subilllatus utilizes many of the same host plants as M. trinodis and M. agilis, it generally avoids large, cultivated sunflower varieties.
• M. illatus forages on asters in summer, but is grayer in color and generally does not appear on large, cultivated sunflowers.
• M. dentiventris is similar in appearance but has faint or indistinct banding on abdomen (wears away quickly), pale hairs on T1, and pale scopal hairs (though this can be hard to see if foraging for pollen). M. dentiventris tends to visits composite asters growing near sand (e.g. Chrysopsis, Boltonia) and is a southeastern species that occasionally turns up in the northeast.

Nesting

Solitary. Underground nests are built adjacent to sunflower host plants, in rich, loamy soil. Not obviously aggregated. Nests are not sealed during foraging, and sometimes, but not always, have a large conspicuous tumulus.

*Nesting biology of M. trinodis is not known, so knowledge of nesting biology for this pair comes from M. agilis.

Foraging

Asteraceae, predominately sunflowers (Helianthus spp.), but also other Asteraceae like cup-plant (Silphium spp.), ironweed (Vernonia spp.), joe-pye weed (Eutrochium spp.), goldenrods (Solidago spp.), and cosmos (Cosmos spp.). Pollen foraging by females is most evident early in the morning.

Natural Enemies

Triepeolus helianthi is a cleptoparasite of M. agilis. Nesting biology of M. trinodis is not well understood, so natural enemies are not known.

References

Parker, F. D., Tepedino, V. J., & Bohart, G. E. 1981. Notes on the Biology of a Common Sunflower Bee, Melissodes (Eumelissodes) agilis Cresson. Journal of the New York Entomological Society, 89: 43–52. 

Page last updated:
February 22, 2023