112 
Mary Beth Roush and Donald C. Tarter 
Instar Head width ranges mm 
I 
II 
III 0.96-1.07 
IV 1.38 - 1.73 
V 2.16 -2.66 
Fig. 3. Head width of all P. postica larvae versus number of larvae. 
Wiggins (1977) stated that phryganeid larvae generally are omni- 
vorous, with a few predaceous for at least part of their life cycle. 
Merritt and Cummins (1978) classified Ptilostomis larvae into two func- 
tional feeding groups: (1) shredders and detritivores, and (2) engulfers. 
Shapas and Hilsenhoff (1976) reported Ptilostomis spp. from the Mecan 
River in Wisconsin that were exclusively carnivorous. Wiggins (1977) 
reported that late instars of P. ocellifera from a British Columbia lake 
were largely predaceous. 
Pupal stage. — Fifty-two pupae were collected in April and May, the 
first on 23 April and the last on 16 May. Most were found embedded in 
logs. April measurements were: x length = 21.84 mm, R = 17-27.5 mm; x 
head width = 2.77 mm, R= 2.4-3 mm. May measurements were: x length 
= 22.23 mm, R = 18-23 mm; x head width = 2.62 mm, R = 2. 3-2. 7 mm. 
Adult stage. — The first adult was collected on 12 May and the last on 
27 May; 31 were collected after dusk. In one hour, 1, 12, 14 and 4 adults 
were collected on May 12, 17, 20 and 27, respectively. Twenty females 
and 1 1 males were collected. A chi-square test showed no significant 
deviation from a 1:1 sex ratio at the 0.05 confidence level. 
No eggs were observed in adult females or in the field. According to 
Wiggins (1973), O. S. Flint Jr. reported that adult Ptilostomis in Michi- 
gan deposited eggs in August, 10 to 20 cm above the water surface of 
streams. Gelatinous masses of eggs were attached to the underside of a 
log and an overhanging bank. 
