Agglutination tests using antibody-sensitized latex particles were developed for the specific detection of the cytoplasmic polyhedrosis virus (CPV) and densonucleosis virus (DNV) of the silkworm, Bombyx mori. With this test 0.75 .mu.g/ml of CPV or 0.5 .mu.g/ml of DNV protein could be detected. The sensitivity of latex agglutination test was 20-30 or 5-20 times higher than that of immunodiffusion or ring test, and was 100-200 times lower than the enzyme-linked immunosolbent assay, respectively. The tests completed within 5 min. Extracts from CPV or DNV-infected silkworm larvae agglutinated latex particles specifically, while there was no agglutination by extracts from normal silkworm larvae. The results showed that the sensitivity and simplicity of this technique for the detection of CPV and DNVC were greater than those of conventional serological techniques such as the immunodiffusion test.