Table 1.

Comparison of the host-flagellate relationship in a hypothetical cockroach ancestor, the wood-feeding cockroach Cryptocercus, and the lower termites. Characteristics of Cryptocercus are assumed to be the state immediately ancestral to lower termites. Key differences between Cryptocercus and lower termites are in red.

	Hypothetical Gregarious Ancestor	Subsocial Cryptocercus	Eusocial Lower Termites
Depends on flagellates to metabolize a cellulose-based diet	no	yes	yes
Parent to offspring vertical transmission of flagellates via trophallaxis	no	yes	yes a
Flagellates die prior to molt of juvenile host	no	no	yes
Juveniles capable of solitary living	yes	yes b	no
Post-molt transmission among family members via trophallaxis	no	no	yes
Transmission of flagellates via cysts in feces	yes	no c	no
Transmission of flagellates via shed hindgut linings d	no	no	no

^a During the subsocial stage of colony foundation. ^b After third instar. ^c Occasional horizontal transmission among siblings after initial vertical transmission of symbiosis is possible. ^d Either their own or that of a nest mate.