Braconid Wasp Cocoons On A Hornworm

I photographed this fascinating interaction between Braconid Wasp cocoons and a Hornworm in my garden near the Ouachita National Forest, Arkansas. This sighting provided a glimpse into the complex relationships that exist in nature, even in a small garden.

Braconid Wasp Cocoons on a Hornworm
A parasitized Hornworm caterpillar hosts the cocoons of Braconid Wasps in an Arkansas garden. The wasp larvae feed on the caterpillar before emerging as adult wasps, demonstrating a natural form of pest control.

When I first noticed the Hornworm on one of my tomato plants, I was struck by the unusual white structures attached to its body. These turned out to be the cocoons of Braconid Wasps. After researching, I learned how this intricate parasitic process works:

  • A female Braconid Wasp deposits her eggs inside the body of a Hornworm caterpillar.
  • The wasp larvae develop within the caterpillar, feeding on its internal tissues.
  • Once mature, the larvae chew through the caterpillar’s skin and emerge. They then spin silk cocoons attached to the caterpillar’s body.
  • Within a short time, the adult wasps hatch from these cocoons, ready to continue the cycle.

While this might seem harsh, it’s an important example of natural pest control. Braconid Wasps are beneficial to gardeners, as they help manage populations of pests like Hornworms, which are known to devour tomato plants and other crops.

Hornworms are the larval stage of the Sphinx Moth, also called the Hawk Moth. Although they are notorious for damaging garden plants, they play a role in the ecosystem. Birds and other predators rely on them as a food source. This dual role—as both a pest and a source of nourishment—demonstrates the balance within nature.

Photographing this interaction presented its own challenges. I used my Canon EOS 7D Mark II camera paired with a Canon EF 100-400mm f/4.5-5.6 L IS II USM lens. Since the caterpillar was perched on a tomato plant in natural light, I hand-held my camera to capture the details.

Technical Details:

  • Location: Near the Ouachita National Forest, Arkansas
  • Date & Time: September 14, 2016, 7:22 AM
  • Camera: Canon EOS 7D Mark II
  • Lens: Canon EF 100-400mm f/4.5-5.6 L IS II USM
  • Focal Length: 400mm
  • Aperture: f/8.0
  • Shutter Speed: 1/250 sec
  • ISO: 1000

The Hornworm remained alive during this stage, though it was parasitized. This is typical with parasitic wasps; the host continues to live and move, even while serving as nourishment for the wasp larvae. This allows the Hornworm to stay in place, ensuring a stable environment for the wasps to develop.

As a wildlife photographer, moments like these remind me how every organism has a role. Even garden pests like Hornworms contribute to maintaining ecological balance, albeit in ways that aren’t immediately apparent. Observing and documenting these processes deepens my appreciation for the natural world, especially in my own backyard.