1979] 
Aiello — Phereoeca allutella 
129 
was able to pull the front part of the case, indicating that other 
prolegs are probably involved as well. The body setae are weak and 
probably play no role in holding the case. 
To move about the habitat, the larva extends the anterior part of 
its body out of the case, walks ahead with its true (thoracic) legs, 
then stops and contracts its body to pull the case up behind. When 
moving at top speed (one pull per second), a larva progresses 1-2 
mm per second on a horizontal surface, and only slightly slower on 
a vertical one. 
When moving within the case, the larva uses both true legs and 
prolegs, plus body extension and contraction, in typical larval 
fashion. 
Larvae 
Larvae chew their way out of their eggs eleven days after oviposi- 
tion. The head is dark; the rest of the larva is white. From the 
second instar on, the tergal and pleural sclerites of each thoracic 
segment are sclerotized and dark, perhaps as protection when the 
larva reaches out of its case. The final instar larvae of three species 
of Phereoeca were described in detail by Hinton (1956). 
Individuals closely monitored during development passed through 
six larval instars. First instar larvae had head capsule widths of 
0.16-0.18 mm. Head capsule width increased with each molt by an 
average factor of 1.34 (range: 1.22-1.46). Final head capsule widths 
ranged from 0.66 mm to 0.78 mm. However, these were all males. 
Larvae of females, collected as final instars, were larger and had 
head capsules as wide as 1.06 mm. Apparently females either grow 
more than males from one instar to the next, or attain a seventh 
instar. Possibly instar number varies among individuals of both 
sexes. 
Case Construction 
Soon after leaving the egg, the larva begins to construct a case of 
silk and tiny particles such as sand, soil, and insect droppings. It 
begins by constructing an arch attached at both ends to the sub¬ 
strate. The arch, which consists of silk on the inside and particles on 
the outside, is gradually extended to form a tunnel within which the 
larva is concealed. Finally the larva closes the tunnel beneath to 
