How Can Monarchs Feed in Pecan Trees?
Can you solve the mystery?

Monarchs Eating in Pecan Trees?

Every fall, as monarchs migrate through Texas, they roost in great numbers in pecan trees. The monarchs appear to be eating something on the leaves. Here is a typical observation:

10/14/05 Nueces River, TX (28N, -98W)
"Almost without fail, monarchs spend the nights in the native Texas Pecan trees by the Nueces River. The ranchers who have been here for years and years think nothing about seeing the monarchs and expect them to be in the pecan trees. They think (whether right or wrong) that there is something on the leaves of those pecans that feeds the monarchs." (Courtesy of Texas Monarch Watch.)

This is surprising, but true! There is an interesting reason for this, but it requires some detective work:

Solve the mystery!
1. Consider these facts about monarch butterflies:
  • Only a caterpillar can chew leaves. An adult monarch butterfly does not have chewing mouthparts, so it could not possibly chew the pecan leaves.
  • An adult monarch can only eat liquids. The adult must sip its food with its "proboscis." The proboscis is a sucking tube that looks like a soda straw.
  • An adult monarch typically drinks nectar. Nectar is a sweet liquid.
An adult monarch butterfly can only sip its food.

The monarch eats with its "proboscis."

Click image for a closer look.

The proboscis is coiled under the butterfly's head when it is not eating.

2. Learn about "aphids."

"Aphids" are another kind of insect that feeds in pecan trees.

Aphids pierce the pecan leaves. They drink the liquid inside called "phloem."
3. Solve the Mystery!

Monarchs can feed in pecan trees because of the aphids. There is a special food-chain connection between them. Do some research! Learn more about aphids. Can you figure out what is taking place?