EGG GUARDING BY MALE ASSASSIN BUGS OF THE 
GENUS ZELUS (HEMIPTERA: REDUVIIDAE) 
By J. Scott Ralston* 
Western Carolina University 
Cullowhee, North Carolina 28723 
Introduction 
Sporadic accounts of parental care of offspring in the Hemiptera- 
Heteroptera have appeared in the literature and are summarized by 
Hussey (1934) and Odhiambo (1959). In all but one or two of these 
cases only the female guards the brood; the only well documented 
exception is the reduviid Rhinocaris albopilosus in which only 
males guard the broods (Odhiambo, 1959). 
The present paper is a summary of observations on the form 
and function of brood guarding behavior of a reduviid species 
( Zelus sp.) in which males guard the brood. My observations 
were made during January and February 1975, in the vicinity of 
Cali, Colombia in a dry tropical forest zone (Espinal and Monte- 
negro, 1962). There the bugs are common in the outer branches 
of Pithecelobium dulce (Leguminosae), a tree locally known as the 
“chiminango.” During the course of this study I observed approx- 
imately 60 different males with broods. 
Egg Structure and Placement 
The cylindrical, dark brown eggs occur in tight masses, with 
about 5 to 15 eggs in each mass. The eggs are about 0.3 mm in 
diameter, about 1.2 mm long and are attached to a branch or leaf 
by one end. Each egg projects from the substrate at a right angle 
and is in direct contact with other eggs in the mass. Freshly laid 
eggs are brown with fine, cream-colored seals at their exposed ends. 
Older unhatched eggs have darker seals and are partly covered with 
a slimy substance. Hatched eggs lack the seal, which is broken as 
the nymph leaves the egg. 
♦Present address: Department of Biochemistry, N.C. State University, Raleigh, N.C. 
Manuscript received by the editor August 8, 1977. 
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