STUDIES ON THE INSECT FAUNA ON SCOTCH BROOM
97
Its second generation is p w e d either on the larvae of A. ulicis or of
A . juacirostre or Bruchidiua inside the broom seeds. The second generation aduite of Habrocytw do not mature until the following season, but
disperse to overwintering eites.
(b) Mesopolobw d i t e r r u n e w (Mayr) (Pteromalidae), is a hyperparasite of H . sequester. Its life history is similar to that of its host,
that is the first generation is on gorse, the second on broom. Rarely it
also hyperparaeitiees Trimp&9 sp. nr. ob8curellua. This hyperparasite
suffered mortality when adults oviposited in Habroeytus larvae that
were too small and also on dehiscense of pods when Mesopolobw larvae
were separated from their hosts.
(c) Aprostocetus tibiulis (Kurdjumov) (Eulophidae) was a rare hyperparasite of Habrocytus larvae and pupae.
(d) and (e) Eupelmua ur0u)nus Dalman (Eupelmidae) and Torymus sp.
nr. micropterw (Walker) (Torymidae) were also rare and occasional
hyperparasites of E~ubroeytua.
(f) Triaapis sp. nr. obscurellw (Nees) (Braconidse) is a parasite of
Bruchidius larvae only. The oviposition period of the parasite and the
host coincide. The eggs are laid in the host eggs, the larva emerges from
the boat larva and pupates within the pod, the adult emerging in the
same season.
(g) Trichogramma sp. paraaitised a small proportion of Bruchidiw eggs
but only on old broom.
3. Population estimates of the two seed b e e c h and the probable
cauae8 of changes in their numbers
Samples from 425 pods from each of the two study areas were
examined weekly. Adult numbers were estimated by beating known
proportions of bushes onto a collecting tray.
The estimatea of Brwhidius populations are summarised in Table V,
those of Apion in Table VI and the causes of changes in their numbers
are donoted by A to F. In Hruchidius some evaluation of these causes
on young broom wma attempted, but the numbers of all stages on old
broom were too low for analysis. The reverse was true of Apion and
only the numbers on old broom are considered. The factors denoted by
A to F are discussed below.
A. (Tables V and VI) Rough approximations of fecundity of Bruchidiua from field data indicated a mean of 235 eggs on young broom and
185 on old bushes. That of Apion on old broom was 310.
B. (Table V) Mortality of the exposed Bruchidiw eggs was very high
and equal to 58.6% in 1960 and 79.1% in 1961 on young broom. On
old broom it was aa high as 96%. The proportions of non-viable eggs
were very high in both areas and it is possible that many of them were
97
Its second generation is p w e d either on the larvae of A. ulicis or of
A . juacirostre or Bruchidiua inside the broom seeds. The second generation aduite of Habrocytw do not mature until the following season, but
disperse to overwintering eites.
(b) Mesopolobw d i t e r r u n e w (Mayr) (Pteromalidae), is a hyperparasite of H . sequester. Its life history is similar to that of its host,
that is the first generation is on gorse, the second on broom. Rarely it
also hyperparaeitiees Trimp&9 sp. nr. ob8curellua. This hyperparasite
suffered mortality when adults oviposited in Habroeytus larvae that
were too small and also on dehiscense of pods when Mesopolobw larvae
were separated from their hosts.
(c) Aprostocetus tibiulis (Kurdjumov) (Eulophidae) was a rare hyperparasite of Habrocytus larvae and pupae.
(d) and (e) Eupelmua ur0u)nus Dalman (Eupelmidae) and Torymus sp.
nr. micropterw (Walker) (Torymidae) were also rare and occasional
hyperparasites of E~ubroeytua.
(f) Triaapis sp. nr. obscurellw (Nees) (Braconidse) is a parasite of
Bruchidius larvae only. The oviposition period of the parasite and the
host coincide. The eggs are laid in the host eggs, the larva emerges from
the boat larva and pupates within the pod, the adult emerging in the
same season.
(g) Trichogramma sp. paraaitised a small proportion of Bruchidiw eggs
but only on old broom.
3. Population estimates of the two seed b e e c h and the probable
cauae8 of changes in their numbers
Samples from 425 pods from each of the two study areas were
examined weekly. Adult numbers were estimated by beating known
proportions of bushes onto a collecting tray.
The estimatea of Brwhidius populations are summarised in Table V,
those of Apion in Table VI and the causes of changes in their numbers
are donoted by A to F. In Hruchidius some evaluation of these causes
on young broom wma attempted, but the numbers of all stages on old
broom were too low for analysis. The reverse was true of Apion and
only the numbers on old broom are considered. The factors denoted by
A to F are discussed below.
A. (Tables V and VI) Rough approximations of fecundity of Bruchidiua from field data indicated a mean of 235 eggs on young broom and
185 on old bushes. That of Apion on old broom was 310.
B. (Table V) Mortality of the exposed Bruchidiw eggs was very high
and equal to 58.6% in 1960 and 79.1% in 1961 on young broom. On
old broom it was aa high as 96%. The proportions of non-viable eggs
were very high in both areas and it is possible that many of them were