Delphacids are generally grass feeders, with a smaller percentage of sedge feeders and fewer still on other plant taxa.  Host use for endemic delphacid species on Hawaii, and probably other islands, is unusual in that nearly all recorded hosts are dicots.  Wilson and colleagues (1994) compiled host data for all planthoppers and presented an evolytionary hypotheses concerning host use.  Urban et al. (2010) examined host use with respect to delphacid higher phylogeny..

I am compiling a list of delphacid host use and will post it here when it has obtained some level of completion. (A draft is here).

Here is a compiled host use list for the Stenocraninae.

References

The best general sources of host information for Delphacids are as follows

General

Wilson, S. W., C. Mitter, R. F. Denno, and M. R. Wilson. 1994. Evolutionary patterns of host plant use by delphacid planthoppers and their relatives. In: R. F. Denno and T. J. Perfect, (eds.). Planthoppers: Their Ecology and Management. Chapman and Hall, New York. Pp. 7-45 & Appendix [host information in the appendix].

China

Ding, J. H. 2006. Fauna Sinica Insecta Vol. 45 Homoptera Delphacidae. Science Press, Beijing, China.

Central Europe

Holzinger, W. E., I. Kammerlander, and H. Nickel. 2003. Fulgoromorpha, Cicadomorpha excluding Cicadellidae. Volume 1. The Auchenorrhyncha of Central Europe. Brill Academic Publishing, Leiden, Netherlands.

Nickel, H. 2003. The Leafhoppers and Planthoppers of Germany (Hemiptera, Auchenorrhyncha), Patterns and strategies in a highly diverse group of phytophagous insects , Pensoft Series Faunistica 28, Sofia, Bulgaria.

Hawaii

Zimmerman, E.C. 1948. Insects of Hawaii, Volume 4. Homoptera: Auchenorrhyncha. University of Hawaii Press, Honolulu, Hawaii.