Hornworms of the genus Manduca can be a major pest of tomato plants. Contrary to the claims of this Mother Earth News letter, hornworms can and do eat the fruit of tomato plants. Our hornworm population was happy to provide photographic opportunities to set the record straight, as we did here.
The species shown here is Manduca sexta, which (according to reference books) goes by the common name of Tobacco Hornworm, even though this is the species that we invariably find on our tomato plants. (This is confirmed in David L. Wagner’s excellent book, Caterpillars of Eastern North America.)
To minimize hornworm damage, we pick them off by hand and smush them with a boot. The trails of droppings are often the first sign that these well camouflaged moth larvae are present.
The photo below shows what hornworms are capable of doing to a tomato planting if populations are left uncontrolled. We didn’t check on this planting for about a week and a half before taking this photo (due to family visits, the fact that this is a winter-keeping variety of tomato that doesn’t need to be harvested until later in the fall, and the slightly out-of-the-way placement of the planting since it was being isolated for seed saving).
In early fall 2013, I “adopted” a Tobacco Hornworm so I could watch its life stages. Having to feed it indoors gave me even more appreciation of just how much one can eat! In October, it formed its pupa:
I kept the pupa in a pot of soil indoors over the winter. In April or May, I unearthed it to check on it. Twitching of the pupa upon contact convinced me it was still alive. I kept an eye on it, and in the days prior to emergence of the adult, the color noticeably darkened and shriveled slightly. This photo was taken on the morning of emergence (on May 27):
It emerged sometime that afternoon, but I missed the actual event.
Here’s the recently emerged adult: