Plant-Insect-Insect-Insect Interaction: Eastern cottonwood, aphids, ants, and signal flies

aphidsantsflies

Aphids, ants, and signal flies on an eastern cottonwood. Photographed 07/03/2013 near Palmyra, Michigan.

The other day I was checking on an eastern cottonwood (Populus deltoides, Salicaceae) that I planted in my yard two years ago. I noticed that many of the leaves were covered in aphids (Hemiptera: Aphididae) in various stages of development. There were also quite a few ants (HymenopteraFormicidae) in close proximity.

aphidsants

Aphids and ants on an eastern cottonwood. Photographed 07/03/2013 near Palmyra, Michigan.

When aphids feed on plants they ingest more sugary sap than they can digest. They excrete the extra fluid as honeydew, a sweet substance that some other insects love to eat. Ants in particular are known to be fond of honeydew, so much so that they sometimes tend aphids like cattle.

aphidsants2

Aphids and ants on an eastern cottonwood. Photographed 07/03/2013 near Palmyra, Michigan.

Ants like these will stick close to the aphids, occasionally feeding on honeydew as they protect their prized sugar cows from harm. When a potential threat gets too close the ants go on the offensive. I tried touching one of the leaves and half a dozen ants flocked to my hand and started biting me:

antbite

Ant attempting to break my skin with its mandibles. Photographed 07/03/2013 near Palmyra, Michigan.

If that wasn’t interesting enough I also noticed another insect in this local food web. A number of signal flies (Diptera: Platystomatidae) were hanging out near the margins of the leaves, and every time the ants were distracted they ran in to get some of the honeydew themselves.

aphidsantsflies2

Aphids, ants, and signal flies on an eastern cottonwood. Photographed 07/03/2013 near Palmyra, Michigan.

As soon as the ants turned around the flies would scurry off and wait patiently for another opportunity. I don’t know if the ants ever manage to catch any of these aphid rustlers, but that would be fun to watch.

Advertisements

About Jeremy Sell

Science and nature nerd.
This entry was posted in Botany, Ecology, Entomology, Organism Interactions and tagged , , , , . Bookmark the permalink.

3 Responses to Plant-Insect-Insect-Insect Interaction: Eastern cottonwood, aphids, ants, and signal flies

  1. Jenny says:

    Thanks for suffering through the pain to provide an excellently illustrative post!

    Like

  2. Wildlife TV says:

    Ants are remarkable animals, so sophisticated yet so unnoticed … until they start biting of course!
    Great post, nice pics.
    -Nick

    Like

  3. Mike Bizeau says:

    Great post, thanks for writing about the interactions and behaviors we usually don’t see or take notice of. I have photographed ants and aphids on several plants. Thanks.

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s