April 1, 1893.] 



KNOWLEDGE 



63 



discoloured by the traffic that goes on amongst it. Ex- 

 ternally it appears to be one continuous mass of interwoven 

 threads, but there are plenty of passages inside, into which 

 the insects retreat on being alarmed. When undisturbed, 



:'*^ 



Flo. .3. — Xest of Small Egger Motli Caterpillar (£rlor/a>:/er laiiextris). 

 (About half natural size.) 



they delight to rest on the outer surface, where they lie at 

 full length, baskmg in the sun ; and it is astonishing to 

 see the rapidity with which, when danger threatens, even 

 a large batch of them will move ofl' and completely disappear 

 into the depths of the nest, leaving no hint outside of their 

 presence within. The nest is something like a whited 

 sepulchre, for though it often looks clean enough outside, 

 especially just after new outworks have been made, it is 

 extremely imtidy within, through the accumulation of cast 

 skins, excrement, fragments of leaves, Ac, which lie about 

 entangled in dirty silk. Thus these web-forming cater- 

 pillars contrast in their habits most unfavourably wdth the 

 scrupulous cleanliness of the truly social insects. In the 

 size and opacity of the nest, as well as in its fixity of 

 position, and in the greater freedom of the caterpillars, 

 which not only lie habitually imtnidc the nest and leave it 

 to feed, but also, when full grown, abandon it altogether, 

 the small egger moth differs entirely from the small 

 ermines. A further difference appears in the act of pupa- 

 tion, for whereas the ermines form a cluster of cocoons 

 inside the nest, the small egger caterpillars leave the nest 

 and form then- cocoons amongst the surrounding herbage, 

 generally near the ground, and in doing so do not cluster 

 together, but each follows its own taste in the selection of 

 a locality in which to construct its strong, egg-shaped, 

 pale brown ease. 



Several other insects, not distantly related to the small 

 egger, construct and inhabit similar nests, especially while 

 young. The best known of these is probably the lackey 

 moth (Clisiocaiiipii nemtria), the flabby caterpillar of which, 

 with its pale blue head marked with two black spots like 



eyes, and its body gaudily striped with red, blue, and 

 orange, is often seen on apple trees and hawthorn hedges, 

 to the former of which it has sometimes done irretrievable 

 damage. The eggs of this moth are glued to the young 

 twigs in the form of a tight-fitting bracelet, encircling the 

 twig, but not covered with down. The gold-tail and brown- 

 tail moths, again, whose stinging caterpillars we mentioned 

 some time ago, construct elaborate nests with partitions 

 and cells, to which in their youth they retire when not 

 feeding, and in which also they hibernate. The pro- 

 cessionary caterpillars of the C'ontinent (Cucthocamjia) form 

 another excellent example of web-forming insects belonging 

 to this group. The nest has but one opening, and this 

 fact seems to be in some way connected with their habits 

 of marching forth in long processions in the most regular 

 order ; for all must pass out at the same spot and in the 

 same direction, and hence necessarily form a definite line 

 of march — in one species, feeding on fir, going in single 

 file, and in the other, feeding on oak, in a wedge-shaped 

 body. Some tropical species, also belonging to the same 

 group, vary the proceedings by forming, when they have 

 come to the end of their larval life, a common nest in which 

 to pass into the chri/salia condition. For example, the 

 caterpillars of a moth found in Natal, and called Auaphn 

 panda, a cream-coloured insect with rusty red streaks on 

 its wings, construct a large spherical chamber on a branch 

 of their food-plant, some eight or ten inches in diameter, 

 making its walls of several layers of rough brown silk of 

 different degrees of consistency. This will accommodate 

 from two hundred to three himdred caterpillars, each of 

 which makes its own slight cocoon of light yellowish silk. 

 These are placed side by side, all pointing towards one or 

 other of the two places of exit, until the whole space is 

 closely packed ; thus the whole structure forms a kind of 

 compound cocoon. 



The " knot-horns '' are a group of small moths not 

 much larger than the small ermines, and amongst them 

 are a number of insects belonging to the genus Ephestia , 

 which feed upon dried fruits and other stored vegetable 

 produce, and hence are commonly found in warehouses. 

 They are gregarious and possessed of wonderful powers of 

 multiplication, and these facts, coupled with their small 

 size, often render their eradication an almost hopeless task, 

 except by the sacrifice of the greater part of the stored 

 goods. One species, E. eluteUn, is the pest of chocolate 

 warehouses. The fragmentary and easily shifting nature 

 of their food, the chocolate nibs, would cause them con- 

 siderable inconvenience, and possibly even danger, as they 

 climb about over the pile ; therefore, to obviate this, they 

 carry their silken threads with them wherever they go, 

 and ultimately spin a large silken sheet entirely covering 

 the stores, while the individual nibs are fastened together 

 in all directions by silken threads ; and thus in course of 

 time the whole store is ruined, becoming an inextricable 

 and loathsome mass of web, cocoa fragments, cast skins, 

 and excrement. Another species, E. Kuhniella, which has 

 lately been introduced, and, notwithstanding great pre- 

 cautions, succeeded in estabhshing itself in London ware- 

 houses, more insidious still in its operations, and more 

 disastrous in its results, similarly attacks flour, spinning 

 its filthy webs over the sacks and amongst the grains of 

 flour, till the whole is rendered utterly unfit for human 

 food. Thus the damage wrought by these insignificant 

 insects is by no means to be measured merely by the 

 amount devoured ; in their attempts to secure themselves 

 amidst the treacherous piles of their easily disturbed food, 

 they spoil with their penetrating webs and their disgusting 

 remains far more than they actually consume. 

 (To he continued.) 



