Nov. 1, 1870.] 



HARWDICKE'S SCIENCE GOSSIP. 



247 



also by the tales which accompanied the deceased 

 birds from their distant and little-known homes. It 

 was stated that they come direct from the celestial 

 Paradise : hence, by the way, their universally-ac- 

 cepted name ; that they live solely off the dew of 

 heaven and the vapours floating in mid-air, and that 

 they never touch the earth. If some doubting 

 naturalist ventured to inquire how the species 

 could be continued under such singularly unquiet 

 circumstances, an abundance of theories cropped 

 up in answer. By some it was asserted that the 

 female retired yearly to her real home, Paradise, 

 whence in due time she returned surrounded by a 

 youthful family. Others taught, that the eggs 

 were deposited on the back of the male, who was 

 furnished with a cavity for the purpose, and that 

 they were hatched by the female as the couple 

 floated on high ; lest, however, she should, like 

 Humpty-dumpty, "get a great fall," she knit her 

 mate's long rich plumes among her own more sober 

 feathers, so as to form what may well be called a 

 true lover's knot. By a few it was thought, that 

 the female simply carried the eggs under her wings ; 

 though how she managed, first to deposit, and then 

 to retain them there, in her never-ending flight, 

 " deponent saith not." 



An old French naturalist, Yigneul-Marville 

 ("Melange d'Histoire Naturelle") accounts for 

 the absence of the legs in a less imaginative, but 

 not less absurd, manner. " When a Manucode is 

 found dead at the foot of a tree, it is always legless 

 — a circumstance which has given rise to the belief 

 that the birds are so born. But this is not the case; , 

 the truth is that the ants which abound in those 

 countries, as soon as they come upon a carcase, in- 

 variably attack the legs first; hence it comes to 

 pass that the bodies sent to Europe appear never to 

 have had legs at all ! " 



It is now known that the absence of the legs is 

 simply due to the rough manner in which the skins 

 are prepared by the natives, who cut them off, as 

 not being needed for ornamental purposes. 



In the accompanying figure, A represents two 

 barbs, from one of which spring a series of pinnae 

 (B), with hooks which overlap and catch another 

 set of pinnae (C) with simple teeth. 



Havre. W. TV. Spicer. 



THE COLOUR OE INSECTS DEPENDENT 

 ON THEIR EOOD. 



fTlHAT the colour of insects is much influenced 

 -*~ by the nature of the plant on which they 

 feed, is unquestionable. If the reason of this in- 

 fluence cannot be pointed out, nevertheless it is 

 a well-ascertained fact that certain larva; do assume 

 a tint corresponding to the plant on which they 



have their abode, according as the latter is light or 

 dark, brightly or sombrely coloured. This is par- 

 ticularly the case with the caterpillars of the 

 Loopers (Geometra), which are sometimes green, 

 like leaves and thin petioles ; sometimes grey and 

 brown, answering to the markings on the bark and 

 twigs of trees. Examples of the former are found 

 in the genera Aspilates, Cidaria, and Acidalia ; of 

 the latter in those of Gnophos and Boarmia. Besides, 

 most of the Loopers have this peculiarity, that 

 when alarmed by a touch, they assume an upright or 

 oblique position ; thus having all the appearance of 

 a broken twig, and in this attitude they will remain 

 immovable for a long period ; so that many of them 

 can scarcely be distinguished from the plant on 

 which they are resting ; indeed, to a superficial 

 observer, they appear exactly like a bit of woody 

 substance. 



The polyphagous larvae— those which feed on a 

 large variety of vegetables— take their colouring 

 from the plants on which they have always subsisted. 

 Eor instance, the caterpillar of Amphidasis hetu- 

 laria, Hiib. — a yellowish-green or bark-colour when 

 on the birch-tree, becomes ash-grey on oak, brown 

 on elm, and on willows and poplars yellowish-green, 

 passing into chestnut on the upper surface. 



In the Bombycid group there are, among others, 

 Liparis monacha, which is a light grey, nearly white, 

 on the Scotch fir, a dark grey on the spruce, and 

 almost black on the larch. Again, the caterpillars 

 of Catocala can scarcely be distinguished from the 

 bark of the ash, oak, poplar, or willow, into the 

 fissures of which they retire during the day. 



The Noctuids, which, as in the case of the 

 Agrotis, subsist entirely upon the roots of g ; asses, 

 are invariably earth-coloured. The naked larvae 

 of Cucullia tanaceti lose their white ground-colour 

 and put on a yellow tint, as soon as, abandoning the 

 leaves of the mugwort and tansy, they confine them- 

 selves to the flowers of the latter. In like man- 

 ner, we are assured by Koch that the larvae of 

 Cheslas spartiaria, Hiib., which subsist on the flowers 

 of the broom (Sarothamnus) are yellow, while 

 others which attack the leaves remain green. 



In all these instances, the change of food-plant 

 affects the colouring of the caterpillar only ; but 

 there are besides cases, and those not rare, in 

 which the perfect insect undergoes important 

 changes from the same cause, not merely in the 

 ground-colour of the body, but even in the markings 

 of the wings. Eor example, the moths of Chelonia 

 caja, Ch. villica, and Ch. aulica, whose larvae have 

 been fed from their youth upon the garden lettuce, 

 are of lighter hue and altogether more simply 

 marked than when they have been supported on the 

 nettle or the deadly nightshade (Atropa Belladonna) . 

 It is found, too, that the caterpillar of Liparis 

 ■monacha which has been supported on an apple- 

 tree produces a moth of a much paler hue than 



