What's special about the Eumorpha species?

In theory, nothing. They're relatively common.

However, they're stunning! And in recent years, I've noticed a decline of the Pandorus Sphinx (Eumorpha pandorus) and the Acheon Sphinx (Eumorpha achemon) on cape cod. Why you might ask? Compsilura, Tachnids, and Brachonids! Those are all parasites that lay eggs in the larvae. These caterpillars have a really high parasitism rate on cape cod (87% and 91% respectively for the two species in 2012*).

The adult moths are stunning, and the larvae, while apparently phallic (I don't see it), are also stunning! Unlike most sphinx moths, they loose their distinctive "horn" after the third instar (when a caterpillar sheds it goes into the next instar, so the third instar means it has shed its skin 3 times).

 

Eumorpha achemon specimen

 

Eumorpha pandorus larvae (with a bonus Darapsa myron in the background)

 

Eumorpha achemon larvae (can you tell the difference between this larvae and the pandorus?)

All photos are my own.

*2012 statistical data based off of field work where 25 larvae of each species were found over the course of two nights.