122
XJ. WALOFF
first 60 cm from the main stem, although about 35% of all the eggs
were laid beyond this range. Once the larvae reach the nodules they are
relatively protected in their early stages, but the great majority of the
third and of the fourth instar larvae feed from outaide. The main c a m
of death of those late larval instara and of pupae wm probably predation. Four of the nine species of Carabidae and seven of the fifteen
species of Staphylinidae tested reacted positively to Sitona in precipitin tests (see Section VIII).
It is impossible to evaluate the long range effects of all the factors
noted in this short study. It is, however, obvious that although fecundity wae halved in 1964 the total number that WM produced and survived until the spring of 1964 was slightly in excess of that in the
preceding year (see Table XIV). The total fecundity in 1963 waa 691
eggs per female, and only 262 in 1964, while the corresponding totals of
mortality to the next reproductive stage were 99.67% and 99.15%.
This occurred because the fall in fecundity WM compensated by a
reduction in mortality in the egg stage; simultaneously mortalities in
the other stages were even slightly greater in 1964. Whether such compensatory situations are common is impossible to say.
The most vulnerable single stage in both years was the early first
instar larva and over 85% of the offspring population died in both
yeara, probably because many of the minute larvae failed to reach their
feeding sites, i.e. the root nodulea.
c. CHESIAS LEGATELLA (SCHIEFFERMUELLER) A N D CHESIAS
RUFATA ( FABRICI US) ( HY DRIOMENID AE , LE PIDOPT ERA)
C. legatella (The Streak), a nocturnal geometrid, is out in September
to November and overwinters in the egg stage. Its caterpillars feed on
the broom leaves and young stems. C. rufata overwinters as a pupa in
broom Iitt'er, the moth emerging from May to July. Its caterpillars feed
on the broom leaves approximately from July to September. It is
interesting that these species of the same genus have very different life
histories and their biology is now being investigated by Mr C. Wall.
Makings (1 966) investigated some factors which determine oviposition
in a series of moths, including C. legatella (see Table XIX). He found
that the moth does not respond to the smell of broom alone, but given
the choice of dead and living broom, it lays all its eggs on the living
plant. If, however, the living plant is covered with muslin, 80 as to
exclude crevices, all the eggs are laid on the dead plant. This indicated
that the response to broom odour provides an essential stimulus to the
chain of reactions terminating in ovipoaition. Palpation of the host
plant wtw also necessary before the moth oviposited and presumably
XJ. WALOFF
first 60 cm from the main stem, although about 35% of all the eggs
were laid beyond this range. Once the larvae reach the nodules they are
relatively protected in their early stages, but the great majority of the
third and of the fourth instar larvae feed from outaide. The main c a m
of death of those late larval instara and of pupae wm probably predation. Four of the nine species of Carabidae and seven of the fifteen
species of Staphylinidae tested reacted positively to Sitona in precipitin tests (see Section VIII).
It is impossible to evaluate the long range effects of all the factors
noted in this short study. It is, however, obvious that although fecundity wae halved in 1964 the total number that WM produced and survived until the spring of 1964 was slightly in excess of that in the
preceding year (see Table XIV). The total fecundity in 1963 waa 691
eggs per female, and only 262 in 1964, while the corresponding totals of
mortality to the next reproductive stage were 99.67% and 99.15%.
This occurred because the fall in fecundity WM compensated by a
reduction in mortality in the egg stage; simultaneously mortalities in
the other stages were even slightly greater in 1964. Whether such compensatory situations are common is impossible to say.
The most vulnerable single stage in both years was the early first
instar larva and over 85% of the offspring population died in both
yeara, probably because many of the minute larvae failed to reach their
feeding sites, i.e. the root nodulea.
c. CHESIAS LEGATELLA (SCHIEFFERMUELLER) A N D CHESIAS
RUFATA ( FABRICI US) ( HY DRIOMENID AE , LE PIDOPT ERA)
C. legatella (The Streak), a nocturnal geometrid, is out in September
to November and overwinters in the egg stage. Its caterpillars feed on
the broom leaves and young stems. C. rufata overwinters as a pupa in
broom Iitt'er, the moth emerging from May to July. Its caterpillars feed
on the broom leaves approximately from July to September. It is
interesting that these species of the same genus have very different life
histories and their biology is now being investigated by Mr C. Wall.
Makings (1 966) investigated some factors which determine oviposition
in a series of moths, including C. legatella (see Table XIX). He found
that the moth does not respond to the smell of broom alone, but given
the choice of dead and living broom, it lays all its eggs on the living
plant. If, however, the living plant is covered with muslin, 80 as to
exclude crevices, all the eggs are laid on the dead plant. This indicated
that the response to broom odour provides an essential stimulus to the
chain of reactions terminating in ovipoaition. Palpation of the host
plant wtw also necessary before the moth oviposited and presumably