308 M. Butler etal. 



Trichoton ypus aloskensis 



A_ 



20 - 



10 - 







iLdI 



Tonytgrsus qreq arius - gr. sp^ 



IL 



T" ■ r 



202- 



301- 



« 201- 



Q. 

 O 



- lOh 

 ro 



-58 



Tonytgrsus i ngequglis 



lUliL 



liUL 



I* 

 • 

 E 

 » 



w 40 1- 



a> 



E 



= 30 



20 



1—69 



10 







10 



Pgrgtgnytgrsus penicillotus 



1—53 



i^ iJltr 



J 



r jl H n n n n 



Chironomus pilicornis 



Aug 



II n H n n 



Jul 



Aug 



Pond J 



Pond G 



FIGURE 7-5. Emergence phenologies of five chironomid 

 species from both Carex (solid bars) and central sediment 

 (open bars) habitats in Ponds G and J during 1976. Traps 

 were cleared at 2- to 3-day intervals from late June through 

 early August. Bar heights represent the number of midges 

 emerging into three traps whose total area was 0.15 /n^ 



Tanytarsus inaequalis from Pond J, nearly all individuals emerging more 

 than 3 days after the population maximum were infested with nematodes. 

 In other ponds emergence of this species was more synchronous. 



The sequence of emergence was consistent between all ponds and 

 years, even when species composition varied. This again suggests the sort 

 of species-specific thermal control of pupal development proposed by 



