I deliberately waited until I had finished my first book before buying the MP-E 65mm macro lens, because I wanted to focus on making a guide to things that people can actually see. Now that I have it, though, it has enabled me to take animal tracking to a very tiny scale, as illustrated by the photos of agromyzid fly vs. parasitoid wasp exit holes in my previous post. Those are details that my naked eye can still make out, but here is an example of something I never would have noticed without that lens. The caterpillar in the photo below is 5 mm long, the larva of Bucculatrix ivella (Bucculatricidae), one of the few leafminers with a common name: the Groundsel Leaf-perforator Moth. It feeds on groundsel (Baccharis halimifolia), and its name comes from what it does after it is done leafmining. Like most Bucculatrix species (the “ribbed cocoon maker moths”), after making a short leaf mine it emerges and eats little patches out of the leaf surface, usually on the underside. The reason anyone bothered to give it a common name is that it has been introduced as a biological control agent in Australia, where groundsel has become invasive.
Anyway, after I took a few photos of this larva, I zoomed in on the LCD screen to make sure it was in focus, and I noticed a little dot.
See it? Here’s a closer crop of the same photo:
Smack in the middle of the first abdominal segment (the first segment without a leg attached to it) is the hole where a parasitoid wasp inserted her ovipositor. As the larva nonchalantly munched away, a wasp larva was living inside it, biding its time. Not long after I took that photo, the caterpillar spun its cocoon on the side of the vial–you can see why they’re called “ribbed cocoon maker moths”:
It even went to the trouble to build a protective silk fence around itself before spinning its cocoon, to keep away predators (hard to see with the white background; here is a clearer example)–but of course it was too late for that. Once the cocoon was spun, the wasp larva rapidly grew and devoured its host, and eleven days after I collected the caterpillar, this little red braconid emerged–a Polystenidea species, according to Michael Sharkey.