June, 1896.] 
Packard: Phosphorescent Organs of Insects. 
61 
THE PHOSPHORESCENT ORGANS OF INSECTS. 
By A. S. Packard. 
The nature of the phosphorescent organs and their physiology has 
never seriously engaged the attention of students in this country, and I 
have thought that some account compiled from the latest and best re¬ 
searches might stimulate inquiry in this country, where fire-flies are 
universally common. 
Phosphorescence is not infrequent in the Protozoa, Coelenterates, 
Worms, and has been observed in the bivalve Pholas, in a few abyssal 
Crustacea, in Myriopods ( Geophilus ), in an Ascidian, Pyrosoma, and 
in certain deep-sea fishes. 
In insects luminosity is mostly confined to a few Coleoptera, and 
besides the well-known fire-flies, an Indian Buprestid (Buprestis ocel - 
lata ) is said to be phosphorescent; also a Telephorid larva. Other 
luminous insects are the Poduran Anurophorus , Fulgora , and certain 
Diptera (Culex and Tyreophora'). 
The seat of the light is the intensely luminous areas situated either 
in the head (Fulgora), in the abdomen (Lampyridae), or in the thorax 
(in a few Elateridte of the genus Pyrophorus). The luminous or photo¬ 
genic organ is regarded by Wielowiejsky and also by Emery as morpho¬ 
logically a specialized portion of the fat-body, being a plate consisting 
of polygonal cells, situated directly under the integument, and supplied 
with nerves and fine tracheal branches. 
tr 
Fig. A. Sagittal section through the hinder end of a male Luciola ; the 
organs above the phosphorescent plate only drawn in outline, s, integument of the 
last segment, somewhat removed by the section-knife from the phosphorescent tissues. 
