COLEOPTERA. 453 



Towards the end of October the perfect insect is already marked 

 out, but it is still soft and weak. It passes the winter in its hiding- 

 place, hardens and becomes coloured at the end of the winter, and 

 shows itself by degrees on the surface of the ground. In the month 

 of April, three years after its birth, the cockchafer emerges from the 

 earth, and commences its attack on the leaves of trees. This long 

 duration of the development of the insect explains why we do not see 

 them every year in the same number. When they have once appeared 

 in great quantities, it is not for three years afterwards that we need 

 expect to see their progeny again in proportionate numbers. It is, 

 then, every three years that we have a cockchafer year like 1865, but 

 in the intermediate years they are never very abundant. For the 

 first year the little larvse do not eat much. They feed then princi- 

 pally on fragments of dung, and on vegetable detritus, and keep 

 together in families. In winter they bury themselves deeply, so as to 

 be secure against frost and floods. Next spring the want of a greater 

 abundance of food forces them to disperse. They then make subter- 

 ranean galleries in all directions, without, however, going far from the 

 place where they were hatched. They begin attacking the roots 

 which they find within their reach ; the damage they do increasing 

 with their size and the strength of their mandibles. Among roots, 

 they seem to prefer those of the strawberry and of rose-trees ; but 

 they do not despise other vegetables, and attack legumes and cereals 

 as well as bushes and plants. The ravages which they occasion are 

 sometimes incalculable ; market gardens are sometimes entirely 

 devastated. Fields of lucerne have been seen partially destroyed by 

 them ; meadows of great extent lose their pasturage ; oat fields die off 

 before they have come to maturity ; and many of the ears of corn fall 

 before they are cut. 



In proportion as they increase in age and in strength — especially 

 in their last year — do they attack also ligneous vegetation. When 

 they have gnawed away the lateral roots of a young tree, the new 

 shoots corresponding to them dry up. The larvae then attack the 

 principal root, and thus bring about the death of the tree. There 

 will be found round the roots of trees thus attacked immense numbers 

 of these worms. M. Deschiens relates that he had seen six hectares 

 of acorns, sown three times in the space of five years with a perfect 

 result, entirely destroyed as many times by the larvae of the cock- 

 chafer. A nurseryman of Bourg-la-Reine suffered, in 1854, from 

 the ravages of these terrible larvse, losses which he estimated at 

 30,000 francs. Others only preserved about a hundredth part of 

 their plants. In Prussia they destroyed, in 1835, ^ considerable 



