First description of polytene chromosomes in biting midges (Diptera: Ceratopogonidae).

Polytene chromosomes are described from secretory cells in larvae of Forcipomyia nigra (Winnertz). They are present in large glandular-trichogen cells at the bases of secretory setae and in midgut cells that were observed by transmission electron microscopy and light microscopy. Polytene chromosomes, isolated from the glandular-trichogen cells using aceto-orcein squash technique, measure 50-200 microm, have braid-like strands of chromatin and no bands, features that are unique within the Culicomorpha.