To start with the most exciting discovery – caterpillar burgers are really good! At the time of our harvest, most of the batch had spun cocoons (more about them later), but we had a couple hundred large silkworms (5th instar) left. Although our primary experiment was to prepare the cocooned pupae in more traditional methods of Vietnam and Korea, the idea was struck upon to make burger patties with the remaining caterpillars. The preparation was simple, the caterpillars were frozen, then blanched and food processed with onion, cilantro and breadcrumbs. The resulting mixture was easily formed into patties and browned nicely when fried. Best of all, when it came time to taste them, they were really delicious. Our conclusion was that they were “better than most veggie patties” – not bad for the first attempt! And they passed another important test: they went great with ketchup – a key litmus test of the North American palate.
On the heels of this smashing success however we concluded that silkworms are not a viable candidate for food source cultivation in North America. There are many pros to raising them: they are already domesticated and their lifecycles are well understood; they cannot survive in the wild so they are not at risk of becoming an agricultural pest; they grow and reproduce very quickly. Indeed at first glance they appear to be highly suited for use as a food source. Nevertheless, the cons simply outweigh the pros. Firstly, the fact that they only eat mulberry is extremely inconvenient. It renders year-round production nearly impossible because mulberry is a deciduous tree. That any silkworm farm also requires a mulberry farm results in a much larger footprint for any operation growing silkworms, whereas other species can subsist on non-specialized, opportunistically available diets and even on the waste streams of other agricultures (for example mealworms can live in just about any form of grain chaff and crickets will eat any past-its-prime vegetable you throw their way). The other major downside to the silkworms is that at their largest size (optimal harvest time), up to 25% of their body mass is composed of their silk glands. Although technically ‘edible’ or at least digestively inert, we are not aware of any particular nutritional value from consuming silk – and the glands harden and become tough and gristly when cooked.
Ok, so silkworm burgers were good, but it’s not worth raising them for that purpose you say – what about the pupae, the initial purpose of the experiment? How were they, and are they worth raising? The silkworm pupae were perfectly edible. One taster had a personal aversion to their taste, but the rest of us felt they were good enough, though nowhere near as tasty as the caterpillar burgers. However it absolutely does not makes sense to raise silkworms to pupae for consumption unless they are themselves a byproduct of a silk production operation. In addition to the issues in the previous paragraph with raising silkworms – the pupae have encased themselves in an incredibly tough protective case that needs to be removed without damaging the pupa inside. Cutting the pupae out of the cocoons and discarding the silk makes little economic sense when silk is so valuable, but processing silk itself is probably too labor intensive an operation to succeed in North America when the same product can be produced at lower cost in Asia.
Co-Founder, Tiny Farms