VI—THE BUTTERFLIES. 
ber at the Waiau, a tributary to that river. Again in 1861 
he captured three on the Rangitikei River near Mr. Birch’s 
run. He also records other captures.’’* About 1868 a long 
series of this butterfly was taken at Nelson by an unknown 
collector, and others were seen and taken there by myself 
in October, 1881; the insect was also bred, by Mr. C. W. 
Lee, at Wangachu in 1879. More recent captures are as 
follows:—In December, 1891, Mr. J. Rutland reported D. 
plexippus as occurring in the Pelorus Valley; in March, 
1892, Mr. A. J. Rutherfurd took a specimen near Otak1, 
and in April of the same year one was taken by Sir James 
Hector at Petone. In 1894 Dr. P. Marshall reported the 
insect as breeding in hundreds, in Wanganui, on plants of 
a species of Gomphocarpus in gardens, but not appearing 
the following summer. On May 15, 1898, several specimens 
were captured at the Girls’ College, Wanganui. <A speci- 
men was observed at Nelson, by the late Mr. Kingsley, on 
January 6, 1904; and two specimens by Mr. Sherlock, at 
Thames, about the same time; three specimens at Makara 
Beach, near Wellington, in May, 1906, and one on Welling- 
ton wharf; one specimen, taken at Otahuhu in 1908, is in 
Mr. E. S. West’s collection; another was seen in Welling- 
ton, by Mr. Bakewell, early in May, 1909; further ex- 
amples at Long Acre, Wanganui, by Mr. Hesse, in 1911; at 
Thames about the same time, and at the Chatham Islands 
by Miss Shand. In 1917 two specimens occurred in the 
Hutt Valley, one taken by Dr. C. M. Hector on 5th Octo- 
ber, and another seen by Mr. Creagh O’Connor on 14th 
October; on the same day a further specimen was seen, by 
Mr. T. C. Cockeroft, in Gollan’s Valley; one specimen was 
detected by Commander 8S. C. Paterson, at Whangarei, in 
December, 1923; one by Mr. C. W. Palmer, at Miramar, 
near Wellington, at the same time; another by school child- 
ren, at Motunui, 15 miles from New Plymouth, on Feb- 
ruary 7, 1924; one seen by Miss Castle, in Sydney Street, 
Wellington, in December, 1925, and another by Mr. C. W. 
Palmer, at Miramar, in February, 1926. From these re- 
cords it will be seen that the insect was observed in New 
Zealand as early as 1840, and has been met with at irregu- 
lar intervals ever since, but in recent years apparently less 
frequently, a corresponding decline in numbers having 
been observed in many of the Pacific Islands, visited by 
Mr. C. L. Collenette, in 1924 and 1925.t These facts have 
more than a purely local interest, for, as pointed out by 
Commander J. J. Walker, in his most interesting account 
of the geographical distribution of Danaida plexippus, its 
arrival in New Zealand, about 1840, seems to have been 
the earliest definite evidence of its occurrence outside the 
American Continentt In the same paper Commander 
Walker records that the butterfly reached Hawaii about 
1845; Caroline Islands, 1857; Tonga, 1863; Azores, 1864; 
Samoa, 1867; Rarotonga, 1869; Tahiti, 1870; Brisbane, 
* * Catalogue of N. Z. Butterflies,” 21. 
~ Ent. Mo. Mag., LXI., 198. 
+ Ent. Mo. Mag., L., 181 et seq. 

° 
~ 
tc 
1 
1870; Melbourne, 1872; Britain, 1876; New Caledonia, 
1881; Society Islands, 1883; Spain, 1886; Canary Islands, 
1888; and France in 1897. The record of the spread of 
this butterfly, almost within living memory, may be re- 
garded as one of the most interesting facts in insect migra- 
tion actually known to us, and is attributed to the artifi- 
cial dispersal of its foodplant by human agency, the butter- 
fly itself having migrated by means of its powerful flight 
aided by the elements, its habit of congregating in great 
swarms and strong migratory instinct assisting. Danaida 
plextpus is a member of an old world genus, and it is 
considered probable that the butterfly originally reached 
North America by way of the Aleutian Islands, possibly 
soon after the close of the glacial epoch. 
The expansion of its wings is from 3% to 44 inches. Above, 
all the wings are rich orange-brown bordered with black; the 
veins are also black. There are two rows of small white spots 
round the margins of all the wings, and several orange-brown 
spots near the apex of the fore-wings. Beneath, the markings are 
similar, except that the white spots are larger, and the hind- 
wings are very pale yellowish-brown. The male has a black 
chitinous scent pocket on vein 2 of the hind-wings which is want- 
ing in the female; the wing-veins in the male are also slightly 
narrower. 
The larva of this insect feeds on most of the different 
kinds of milkweed (Asclepias), and also upon dogbane 
(Apocynun). The following account of its habits is taken 
from Professor Riley’s ‘‘ Third Annual Report of the 
Noxious, Beneficial, and other Insects of the State of Mis- 
souri,’’ supplemented by accounts by Messrs. Seudder and 
Frohawk :— 
The ege is usually deposited on the under side of a leaf, 
and is conical and delicately reticulate, with about twenty longi- 
tudinal ribs, and many fine transverse strie. It is yellowish 
when first deposited, but becomes grey as the embryo within 
develops. 
In about five days after laying the egg hatches, and the 
young larva as soon as hatched usually turns round and devours 
its egg-shell—a custom very prevalent with young caterpillars. 
At this stage it differs considerably from the mature larva; it 
is perfectly cylindrical, about 0°12 inch long, and of much the 
same thickness throughout. The head is jet black and polished; 
the colour of the body is pale greenish-white, with the anterior 
and posterior horns showing as mere black conical joints, and 
with two transverse-oval black warts, nearer together, on the 
first joint. It is covered with minute black bristles, arising from 
still more minute warts. 
When the young larva is three or four days old a dusky 
band appears across the middle of each joint, and by the fifth or 
sixth day it spins a carpet of silk upon the leaf, and prepares for 
its first moult. After the first moult the anterior horns are as 
long as the thoracic legs, the posterior ones being somewhat 
shorter; the characteristic black stripes show quite distinctly, 
but the white and yellow stripes more faintly. After this it 
undergoes but slight change in appearance, except that the colours 
become brighter, and that at each successive moult the horns 
become relatively longer. There are four moults, and the inter- 
vals between them are short, as the larve frequently acquire 
their full growth within three weeks from hatching. 
The full-grown larva is about 24 inches in length. The 
head is smooth and rounded, yellow, conspicuously banded with 
black. The body is cylindrical, tapering slightly at each end, 


