164 
Psyche 
[June 
Field Occurrence 
Larvae of the horn fly, Haematobia irritans Linnaeus, occurred 
in bovine feces in pastures in association with adults and larvae of 
Platystethus spiculus. 
There was no continuous coincidence of P . spiculus larvae and 
adults with H. irritans larvae (Figs. 6-8). Therefore, alternative 
food would have been necessary to sustain P. spiculus during period 
of H. irritans scarcity or absence. 
The occurrence of P. spiculus larvae was exceptionally low in the 
manure habitat, certainly not sufficiently dense to account for the 
comparative high adult abundance (Figs. 6 & 7), and no larvae 
were detected in dry pastures (Fig. 8). 
It appears that P. spiculus adults are initially attracted to fresh 
bovine feces in green pastures where some eggs are laid (Fig. 6). 
Attraction to dry pastures is not as great, and apparently no eggs 
are laid judging from the absence of larvae (Fig. 8). The adult 
density is maintained for at least 24 hrs (Fig. 7). The majority of 
the larvae of this species may occur subterraneously below and sur- 
rounding the bovine fecal droppings. 
Hinton (1944) has shown that in the European P. arenarius 
(Fourcroy) larvae and adults feed on manure and are facultative 
feeders on carrion; that eggs are laid in a brood chamber in or 
partly beneath manure and protected by the female until hatched. 
Whether similar sub-social behavior exists with the American spe- 
cies has not been determined. 
Literature Cited 
Hinton. H. E. 
1944. Some remarks on sub-social beetles, with notes on the Biology of the 
staphylinid, Platystethus arenarius (Fourcroy). Proc. Royal Ent. Soc. 
London. (A): 19: 115-118, 15 Figs. 
Legner, E. F., G. S. Olton, R. E. Eastwood and E. J. Dietrick. 
1975. Seasonal density, distribution and interactions of predatory and scaven- 
ger arthropods in accumulating poultry wastes in coastal and interior 
southern California. Entomophaga. 20 (3): 269-283. 
Moore. I. and E. F. Legner 
1971. A review of the Nearctic species of Platystethus (Coleoptera:Staphylini- 
dae). Pan-Pac. Entomol. 47 : 260-264. 1 Fig. 
Paulian, R. 
1941. Les premier etats des Staphylinoidea. Etude de Morphologie Comperee. 
Mem. Mus. Nat. Paris, n. ser., 15: 1-361; 1365 Fig., 3 L. 
