188 
Psyche 
[Vol. 92 
Table 1. Developmental Rates of Eggs, Larval Instars, and Pupae of Meronera 
venustula (Erichson) 
Stage 
Duration 
x ± S.D. 
N 
Egg 
1-4 days 
2.8 ± 1.2 
17 
Instar I 
1-4 days 
1.8 ± 1.1 
9 
Instar II 
1-2 days 
1.4 ±0.5 
7 
Instar III 
4-5 days 
4.5 ±0.71 
2 
Pupae 
4-5 days 
4.5 ±0.71 
2 
age duration of the egg stage was 2.8 days. The first instar lasted an 
average of 1.8 days, the second 1.4 days and the third 4.5 days. 
Survival of larvae beyond instar I was not good, especially during 
the latter stages of the study, during which laboratory temperatures 
fluctuated widely. It is not clear whether reduced survival of larvae 
was a result of temperature regime, temperature fluctuation or other 
inadequate environmental conditions. Only 2 larvae completed 
development to the adult stage though several other third instar 
larvae were killed for study. 
Both larvae which reached the prepupal stage completed pupa- 
tion without production of a cocoon. Production of a silken cocoon 
for pupation has been noted among a variety of aleocharine larvae 
(see Ashe 1982, Frank and Thomas 1984) and is presumed to be 
characteristic of members of this subfamily. Pupation of M. venus- 
tula larvae without production of a cocoon is therefore quite unex- 
pected. One of the 2 larvae produced a thin, shiny deposit on which 
the pupa lay. In the other, no such deposit was observed. It is 
possible that this deposit represents a vestigial or poorly formed 
pupal cocoon, but this cannot be confirmed without additional 
observations. 
Though these larvae did not form a pupal cocoon, it does not 
represent positive proof that larvae do not form a cocoon for pupa- 
tion under natural conditions. A number of conditions in the labora- 
tory cultures, including nutrition, humidity, temperature, substrate 
and others, may not have sufficiently approached natural condi- 
tions. Still, lack of a pupal cocoon is suggestive and deserves further 
investigation. 
The form of pupal cuticular modifications may have a bearing on 
this problem. Examination of the pupal exuvia showed that the 
pupa of M. venustula is covered with a distinctive arrangement of 
very long, stiff cuticular spines. These spines are much more remi- 
