The Fergusson Island form, which may be distinct from H. rufescens proper, is infected by the nematode Moaciria moraveci.
The only known host is a frog in the genus Hylophorbus from Fergusson, close to but perhaps distinct from Hylophorbus rufescens; it is present in 10 out of 21 specimens examined.
Xylophanes rufescens | Polyergus rufescens | Hylophorbus rufescens |