104 
Psyche 
[March 
merited eyes. It has a head width of 0.28 mm, widest girth across 
the thorax of 0.3 mm, and a body length of 0.9 mm. It is not pro- 
vided with abdominal prolegs, as described by Brauer (1855, fig. 7, 
pi. Ill; 1863, fig. 2, pi. XIV) for B. westwoodi, but the terminal 
abdominal segment does serve, and very effectively so, as a holdfast 
as he believed. 
The two hatched larvae were placed on a small mat of damp moss 
into the sod of which they speedily disappeared. Seventeen days later 
the larvae were torpid, stretched out and turgid, and remained so for 
the next four days. At that point the head capsule was 0.3 mm wide, 
the metanotal girth 0.38 mm (the broadest portion of the thorax), 
and the total body length 1.04 mm in one, 1.42 mm in the other. If, 
at this point, they were ready for the first larval moult, then the first 
instar is completed within 16 to 17 days at 20°C. Unfortunately 
observations had to be discontinued, and the larvae were preserved. 
Striibing (1950, 1958) has shown that the rate of development in 
B. hyemalis is strongly affected by temperature and, unlike the adult, 
eggs and larvae develop only very slowly, if at all, at the low tem- 
peratures of winter. Indeed the egg remains dormant through the 
winter months, normally hatching in the period from the end of 
March to mid-April. Hatching is almost certainly earlier in the case 
of B. notoperates for, by the close of January and February, air 
temperatures above 20°C and warm sunshine are not uncommon in 
its habitat on Mt. San Jacinto. 
Larva 
During the last two weeks of August and in September, larvae, 
pharate pupae (Hinton 1971, 1973), and pupae of B. notoperates 
are found in the sod of host mosses, amid the rhizoids. The apparent 
larvae are of two size classes : ( 1 ) with a mean head length from the 
tip of the labrum to the occiput of 0.49 mm, range 0.47-0.52 mm, 
and a coefficient of variation (V) of 5.7 (6 specimens), and (2) 
with a mean head length of 0.68 mm, range 0.59-0.87 mm, and a 
surprisingly large V of 9.7 (23 specimens). Though smaller larvae 
of the second class proved to be males, and the larger females, the 
size distribution is not bimodal. No doubt their high coefficient of 
variation is in part a consequence of two factors: a sexual difference 
in size at the last instar, and the consequences of the larval-pupal 
apolysis that closes the larval stage and which I did not detect until 
later. They proved a heterogeneous lot of last instar larvae and 
pharate pupae. 
