Vol. 70 
PSYCHE 
No. 2 
June, 1963 
THE VENOM AND POISON GLANDS OF 
PSEUDOMYRMEX PALLIDUS (F. SMITH) 
By Murray S. Blum 1 and Philip S. Callahan 2 
In the United States, the small subfamily Pseudomyrmicinae is 
represented by several species which are known to sting severely. 
Probably the most common species in the southeastern area is Pseudo- 
myrmex pallidus (F. Smith). As part of a program of study on ant 
venoms in our laboratories, this paper presents a characterization of 
the venom of this species, a description of its poison apparatus and a 
study of the reaction of human beings to its sting. In addition, the 
possible nature of the venoms produced by the F ormicidae is discussed. 
The Poison Gland 
The poison gland of Pseudomyrmex pallidus is quite similar to that 
of Solenopsis saevissima , the imported fire ant, and the reader is 
referred to Callahan et al. (1959) for histological descriptions of the 
glands and sting of that species. As in the fire ant, the main gland 
of Pseudomyrmex pallidus is a rounded organ (Fig. iD) consisting 
of glandular collecting ducts which branch into lateral ducts that 
reduce in size and lead to the secretory cells. The round gland is 
inserted into an invagination of the tunica propria (E) which forms 
the poison sac. The stored poison of the sac empties through a main 
collecting duct (F) into the base of the sting bulb (H). There are 
two extremely long (.49 mm) free poison glands (A) which lead 
by way of a single neck (C) to the convoluted poison gland (D). 
The collecting ducts of the free glands (B) unite at the neck. In 
proportion to the rest of the organ, the neck is considerably longer 
(.13 mm) and the gland narrower than in the fire ant. Dufour’s 
gland (H) is extremely large in relation to the main poison gland, 
being .4 mm in length or 4/5 the length of the duct and sac of the 
department of Entomology, Louisiana State University 
department of Entomology, Louisiana State University; present address, 
Southern Grain Insects Laboratory, U.S.D.A., Tifton, Ga. 
Manuscript received by the editor August 10, 1962. 
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