Embryonic and larval development retarded, ring gland, salivary glands, gastric cecae and most imaginal discs fail to reach normal size before late larval lethal phase. Ventral ganglion fails to condense and the brain hemispheres are undersized, and at death, large melanotic tumours resulting from abnormalities in hematopoiesis are present in the body cavity. Source of the hemocytes is a hyperplastic lymph gland, which contain lamellocytes (normally not found in lymph gland) in process of abnormal self encapsulation.

Neoplastic growth and melanotic encapsulation of the lymph glands. Transplanted lymph glands cause melanotic tumour formation and premature host death.

Melanotic tumour formation and lethality are due to the same mutation. Mutations exhibit incomplete penetrance and expressivity of the melanotic tumour phenotype. Small and/or abnormally shaped brain. Garland cells found at the junction of the oesophagus and proventriculus are melanized. Hemizygous males exhibit hypertrophied lymph glands.