07 de septiembre de 2022

Aphis nerii - an identifiers guide to Oleander Aphids

Little yellow blob insects on your wilted milkweed plants? Odds are, you’re looking at Oleander aphids! Despite their common name referring to Oleander, the species is more generalist and often found on related plants, such as vinca, milkweed, and dogbane. In the United States, it is most commonly observed on milkweeds.

A. nerii is relatively distinctive and easy to identify, but there's currently only two users (@glmory and me, @mydadguyfieri) consistently keeping up with confirming observations of this commonly observed species. Because it’s invasive and is likely to have a negative impact on populations of native aphids which feed on milkweed and are more specialized (Myzocallis asclepiadis, monophagous; Aphis asclepiadis), it would be beneficial to have more people helping out with this species!

Key Traits for Identification

Bright light orange/yellow color, uniform shade throughout.
All appendages dark/black, including
Legs
Antennae
Cornicles (pronounced tubes on the abdomen)
Alates are winged adult aphids, and they look different than the common wingless form.
Can be found in colonies or individually (dispersing)
Clear wings tented over body, large in relation to body.
Still yellow/orange, with darkened thorax

Life Cycle and Reproduction
Parthenogenic
Females reproduce through cloning: no need for fertilization
No males in wild populations
Vivaporous
Give live birth (rare among insects)
Produce nymphs instead of eggs

Occasionally Observed in Colonies

Various sizes of aphid on one plant:
This is the result of the vivaporous reproduction.
Nymphs appear very similar to apterae (wingless) adults, but smaller.
Large colonies may be composed of nymphs and adults.
Exuvia:
Shed exoskeletons of molted aphids left behind on plant.
Parasitized aphids
Swollen, brown or black, round aphids.
Referred to as “mummies”
These individuals have been parasitized by tiny wasps
Pupa develop inside the shell of the aphid
Adults cut a whole in the aphid to emerge

Often confused with:

Other aphids
If on milkweed, likely one of the native milkweed aphids.
Aphis asclepiadis - Darker brownish color, Appendages not black
Myzocallis asclepiadis - Very small, often more scattered, Light yellow, orange bars/spots
If other color, could be another member of Aphididae.

Heteroptera
Especially Lygaeinae nymphs.
Nymphs (and adults) of species like Lygaeus kalmii (small milkweed bug) or Oncopeltus fasciatus (large milkweed bug) are orange/red and found on milkweed.
Young instars can be quite small, have a tendency to congregate, and are foreign to most observers, and therefore often confused with aphids. Computer vision also has trouble differentiating.

Ingresado el 07 de septiembre de 2022 por mydadguyfieri mydadguyfieri | 0 comentarios | Deja un comentario

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