Kollar's Vier Hauptfeinde der Obstgarten. 173 



they are usually laid, they can be found out with very little trouble ; particularly 

 as they are not laid singly, but are mostly found in large or small heaps. 



As to the length of time the egg remains in that state, it may only be 

 observed, that it is very various, according to the kind of butterfly or moth. 

 Many kinds lie only a few weeks before the young caterpillar makes its appear- 

 ance, while others lie for months, and sustain the severest cold before they are 

 hatched. At all events, the eggs remain sufficiently long to enable any one to 

 destroy them without much loss of time, after the knowledge necessary for 

 doing so is obtained. 



It now remains to show what becomes of the caterpillar when it has attained 

 its full growth; whether it immediately changes to a butterfly, or whether it 

 passes any length of time in an intermediate state. 



The duration of the caterpillar, like that of the egg, is very various. There 

 are caterpillars which remain many months in a worm-like form, while there are 

 others that undergo a change in the space of a few weeks ; and the longer the 

 period of their caterpillar state lasts, the more injury, of course, is done to the 

 trees on the leaves of which they feed. Many caterpillars which are hatched 

 at the end of summer feed during the autumn on the trees, and then enclose 

 themselves in a nest of their own making, lie dormant during the winter, and 

 awaken in spring when the young leaf and blossom buds make their appear- 

 ance, to recommence their operations, which in a few weeks, nay even days, 

 effect the devastation in gardens which we have witnessed through large 

 extents of country. The rapacity of many caterpillars is so great, that a 

 single one will consume leaves several times the weight of its own body in 

 twenty-four hours ; and it is only in that way that the rapid and total disapear- 

 ance of the leaves from trees can be accounted for. 



Changing the skin is peculiar to caterpillars. Every caterpillar during its 

 worm-like appearance casts its outer skin several times ; and many of them 

 vary their colours at the different periods of changing, so that, all of a sudden, 

 apparently quite a different insect is seen on the trees, and nobody can explain 

 how it comes there. This changing the skin continues till they are fully 

 grown ; and, when they have changed it for the last time, they appear in a 

 form totally different from their former state. They lose their feet, their 

 bodies become shorter, but thicker ; and frequently they are enveloped in a 

 silky web, or suspended by means of one or more threads from the branches 

 of trees, or attached to their trunks, or to walls or hedges. This form of the 

 caterpillar is called a pupa. 



During pupation, nourishment is no longer wanted ; and, therefore, when 

 the insect enters this state, we observe a sudden cessation of the devastation of 

 our fruit trees. The caterpillars disappear, without our being aware where 

 they are gone to, unless we are familiar with their metamorphoses. The 

 state of pupation lasts, according to the kind of insect, a few weeks, a few 

 months, or even a few years. The butterfly at last emerges from the pupa, 

 which, as it only sips sweets from the flowers, does no more injury to the 

 trees than the pupa ; but it leaves a new succession of caterpillars in our 

 gardens, as we have already mentioned, that do the injury. 



I have observed that, almost everywhere, the picking off of the insects ceases 

 as soon as the caterpillars disappear, although the branches and stems of the 

 trees may be thickly covered with pupa?, into which the caterpillars have 

 been transformed. This neglect, which in the following year is punished by 

 the repeated failure of the crop, is only occasioned by the want of knowledge 

 of the history of the caterpillar; because, if it were known that the motionless 

 pupae on the stems and branches are the caterpillars transformed, they 

 would certainly be taken down, as it is much easier to do so, than to destroy 

 the living caterpillars which are crawling all over the tree. 



The pupae, besides, are a very agreeable food for many kinds of poultry, and 

 particularly for pigs. 



As I have now given a general idea of the origin of the caterpillar, its 

 growth, and what at last becomes of it, I will proceed to the description of 



N 3 



