PHENOLOGY AND LIFE HISTORY OF THE FILMY 
DOME SPIDER (ARANEAE: LINYPHIIDAE) 
IN TWO LOCAL MARYLAND POPULATIONS* 
By David H. Wise 
Department of Biological Sciences 
University of Maryland Baltimore County (UMBC) 
Catonsville, MD 21228 
Introduction 
The filmy dome spider Neriene radiata (Walckenaer) [= Linyphia 
( Prolinyphia ) marginata C. L. Koch; Araneae, Linyphiidae] spins a 
fine, dome-shaped web in the understory vegetation of temperate 
forests. Early accounts suggested that this species has a typical 
annual life cycle; however, later research uncovered indirect evi- 
dence of a mixed life-history pattern in a Michigan population of N. 
radiata (Wise 1976). Seasonal changes in composition of this popu- 
lation strongly suggested that some hatchlings emerging from egg 
sacs laid in the spring developed rapidly, matured by August and 
reproduced before the end of the season. Other progeny of spring- 
maturing adults apparently displayed a typical annual life cycle, 
over-wintering as juveniles and maturing the next spring. Since this 
type of life cycle had not been reported often for spiders, I decided 
to explore it in more depth. 
The research reported here had two major goals: 
1) To describe the phenologies of two different local popula- 
tions of N. radiata in Maryland, and to compare them with the 
phenology of the more northern Michigan population. Such a com- 
parison would indicate whether or not the length of the growing 
season might influence the species’ life history pattern. 
2) To obtain direct proof of two types of juveniles in the popula- 
tion at the end of the spring reproductive period — rapid developers, 
and those that over-winter before becoming mature. The goal was to 
confirm the previous interpretation of the observed phenology, 
which was based upon indirect, nonexperimentally derived evidence. 
* Manuscript received by the editor August 1 , 1984 
267 
