Recently, Hyrsl et al. (2011) demonstrated that the common fruit fly, Drosophila melanogaster as an immune response can form the blood (hemolymph) clots and protect against infection by an entomopathogenic nematode (Heterorhabditis bacteriophora) and its symbiotic bacterium (Photorhabdus luminescens). Read following papers for more information on the interaction between fruit fly and entomopathogenic nematodes.
Hyrsl, P., Dobes, P., Wang, Z., Hauling, T., Wilhelmsson, C. and Theopold, U. 2011. Clotting Factors and Eicosanoids Protect against Nematode Infections. Journal of Innate Immunity 3: 65-70.