The Gregarious Phasmid
Head above, behind the antennæ, with several impressed longitudinal
lines, antennæ twenty-four jointed, about the length of the anterior
legs in the male, shorter in the female. Prothorax narrower than
the head, and becoming narrower to its junction with the mesothorax,
its length being about equal to the length of the head behind the
antennæ; the mesothorax is rather narrower and scarcely longer than
the prothorax except at its base, where it widens out; it is covered
beneath and on the sides with small tubercles, and on the back with a
double row of five larger tubercles; the metathorax is longer than the
mesothorax, and much wider ; it is sharply tuberculated beneath, as are
also, thouglh in a less degree, the abdominal segments. The tegmina are
rather pointcd - in the female half the length of the wings, in the male
about one-third. The wings are moderately large and equal in both sexes.
The legs are rather short; the hind femora strongly dentated beneath on
the inner and outer edge, with a deep groove between; the intermediate
femora are armed in the same way, but not so strongly; and the anterior
are grooved beneath, but not dentated. The basal joint of the tarsi is
a little the longest, except in the intermediate legs.
The specimens have been in spirits and therefore it is impossible to make
out the colouration with certainty, but the body seems to have been of a
reddish-brown, almost black beneath, the wing coverts yellowish, with the
median carina brown, the costal area of the wings brownish-yellow, and
the wings themselves hyaline, without any visible rosy tint. Length of
male three inches six lines; the female is not longer nor bulkier than
the male. This
uniformity of size in the sexes, if constant, is, I believe, quite
unprecedented in this family of insects.
the orange to brownish yellow base to the pre-anal part of the wing
(the coriaceous “costal field”); the shape of the operculum,
which is only very gently curved for most of its length, but sharply
so cephalad, and bears a few small laterocephalic teeth; and the
emarginate caudal margin of the poculum. (Key, 1957)
by the orange-yellow proximal patch on the remigium of the hind wing.
male and female volant
distinguished by the orange-yellow proximal patch on
the remigium of the hind wing.
In this image of a nymph, note the 2 rows of 4 bright red dots (short
spines) on the thorax. These are quite prominent on the nymph; they
are present but less prominent on the adult.
The black dot between the mid - and hind-wings is also prominent on
earlier instars, when the wings are less developed.
Lifespan: nypmhs take 3 months to mature,
the adult stage a further 3 months.
Eggs: dropped singly on to the forest floor beneath the crown of the
tree on which the female is feeding. Most of the eggs hatching in the
field are from fertilized females, but a small percentage may develop
parthenogenetically. The eggs lie amongst the forest litter for up
to eighteen months and sometimes longer before hatching. Generally no
development of the embryo is perceptible until the first summer following
oviposition, when development takes place though hatching is usually
delayed by a diapause until the next spring. In a small number of cases
the eggs develop and hatch within one year but some do not hatch until
the third season after oviposition.
Eggs from unmated females of P. wilkinsoni yielded female
individuals only, and thus the parthenogenesis appears to be thelytokous,
however it is rare (1.4%).
(from Campbell & Hadlington, 1967)
Nymphs hatch between late October and November, usually
during the early hours of the morning, if conditions at the time of
hatching are very dry or the egg is free to move, the nymph may be unable
to free its third pair of legs.
There are seven (male) or eight(female) nymphal instars,
growth usually being complete by mid-January.
(from Campbell & Hadlington, 1967)
arborial, top of host plants (not necessarity top of canopy)
Most of the Eucalyptus species are acceptable as food, though
there are preferences within the genus. While no quantitative tests
have been done on food preferences it has been noted in nature that
the narrow-leaved “peppermints” E. radiata Sieb. and
E. robersoni Blakely, the broad-leaved “peppermint”
E. dives Schauer and the “gums” E. viminalis
Labill., E. huberiana Naud., E. dairympleana Maiden,
E. mannifera (A. Cunn. Herb.) Mudie, E. stellulata
Sieb., E. pauciflora Sieb., and E. bicostata Maiden,
Blakely and Simmonds appear to be favoured species, and are the first
to be defoliated. Other species which are known to have
been severely defoliated are E. laevopinea R. T. Baker,
E. obliqua L'Hérit., E. delegatensis, R. T. Baker,
and E. fastigata Deane and Maiden, though these appear to be
less favoured than the former groups. E. andreana Naud. is an
acceptable species and has been used for most laboratory rearings.
Some Eucalyptus species are avoided and these will only be eaten
when there is no choice of food.
(Campbell & Hadlington)
Forrestry Commission of N.S.W reared this species for may years
while studying it.
NE coastal, SE coastal, Murray-Darling basin, QLD, NSW
Not endangered. Known to occur in plage proportions from time to time.
Kentromorphic phase differences have been reported
(Key 1957) in the
Podacanthus wilkinsoni which sometimes reaches high population
densities. In the nymph, the pro-cryptic low-density phase is rather
uniform and usually green, whereas the conspicuous, supposedly aposematic,
high-density phase is patterned with black, yellow and sometimes white.
A mean density of one insect per eucalypt branchiet is sufficient to
induce the extreme high-density pattern, while the low- density extreme
occurs at less than one per 20 branchlets. Intermediate patterns appear
at intermediate densities, or in response to density change. The species
also shows morphometric phase differences analogous to those of locusts.
There is apparently no correlation between density and activity, and no
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[I already have this one, except for plates 5 and 6, and possibly
page 159 (references). He also refers to figure 3 in the text, but none
appears in my copy; it may be on page 159.]
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