Step 1. Wait at the eggs for a parasitoid wasp to arrive.
Step 2. Photograph the wasp laying her own eggs into her target, like so:
Step 3: Marvel at how a fully developed wasp in all her intricate detail is an order of magnitude smaller than the egg of a butterfly.
What's going on here?
Scarcely any resource in nature goes untapped by some other organism looking to eat it. Small size is not a complete defense. Insect eggs, diminutive though they are, are plagued by even tinier insect parasites that develop inside them. A few days after the parasite arrives, these eggs will hatch out wasps in the place of a caterpillar.
Even more bizarrely, the parasite itself isn't immune from further attack. Other wasps specialize on the larvae of the egg parasitoids, and a second wasp may well come along to parasitize the parasite. Life can be fractal.
(Ok, the real trick to this magnification? I used Canon's MP-E 65mm 1-5x macro lens at 5x, and I approached from a low angle to elevate the subject. And, thanks to the excellent Green Hills Butterfly Ranch for hosting the photo session.)