1967] 
A ndrews — Ptinus 
201 
two common species at the study site may be attributed to peculiar 
climatic and biotic features of the area (Tropical Dry Forest, 
terminology of Holdridge, 1964). Collecting was done in mid-Feb- 
ruary, towards the end of the dry season (near Canas, long and 
severe, Nov.-Apr., rainfall: 0-47.5 mm/mo, 1965 data, Anuario 
Meteorologico) . There are several reasons why the dry season may 
be the most favorable period for breeding of these two species. ( 1 ) 
During this time their microhabitat, the coati scat, becomes dry and 
remains suitable for the feeding and development of the larva. Mois- 
ture and heavy rainfall would tend to wash apart exposed scats and 
result in rapid decomposition. (2) Because of the availability of 
water there, animal life becomes concentrated along rivers, especially 
so towards the end of the dry season. Coati scats are also concentrated 
in this localized area, thus augmenting ptinid breeding. It seems 
probable that during the rainy season (May-Oct., rainfall: 41-371 
mm/mo) populations of these species would be much lower because 
scats would be dispersed over a wider area and suitably dry scats 
would be less common. 
addendum : Subsequent to submitting this paper, I have had the 
opportunity to examine rainy season sweep samples from the study 
area. Neither Ptinus latefasciatus nor P. costaricensis was present 
in the extensive samples (800 sweeps in each area) from the river- 
bottom forest or immediately surrounding area. Dr. D. H. Janzen 
kindly provided access to sweep samples that he took on July 20, 1967, 
at Taboga, Costa Rica. 
Literature cited 
Anuario Meteorologico. 
1965. Ministerio De Agricultura Y Ganaderia, Servicio Meterologico 
Nacional, Seccion Climatologia, San Jose, Costa Rica. 
Boving, A. G. 
1956. The mature larva of Ptinus calif ornicus and a discussion about 
justification of Ptinidae as a valid family of beetles. Ent. Medd., 
27: 229-241. 
Brown, W. J. 
1959. Niptus Boield. and allied genera in North America. Can. Ent., 
91: 627-633. 
Fall, H. C. 
1905. Revision of the Ptinidae of Boreal America. Trans. Am. Ent. 
Soc., 31: 97-296. 
Gorham, H. S. 
1883. Biologia Centrali-Americana, Insecta, Coleoptera, 3 (2): 194-198. 
Hall, D. W. and R. W. Howe. 
1953. Revised key to larvae of Ptinidae associated with stored prod- 
ucts in Britain. Bull. Ent. Res., 44: 85-96. 
