IxTRODUCTio.y. xxiii 



suffice to kill a plant. Our forests suffer little from the attacks of insects csmpared with those of 

 the Continent, where it sometimes happens that large tracts of forest are completely destroyed. One 

 reason of our immunity is that extensive pine forests like those of the Continent are rarely met with 

 in England, and that this tree is subject to the attacks of the larvae of many moths which are either 

 very rare or wholly unknown amongst us. When there is an extraordinary appearance of destruc- 

 tive larva;, their ravages sometimes continue for one season only, but more frequently for several 

 seasons, during which their numbers continue to increase ; but after a few years, they frequently 

 disappear almost suddenly, in consequence either of disease, or from the abundance of their 

 parasites ; for, as each infected larva usually furnishes food for many ichneumon larvae, the latter 

 naturally tend to increase at a much greater ratio than those of their prey. It thus frequently 

 happens that after any particular larva has been unusually abundant during one year, it may be 

 difficult to find one which is not ichneumoned during the following season. Among the larvae 

 which thus increase to a devastating extent at intervals on the Continent, we may mention those of 

 Eiitriclia Pini and Psilura MonacJia. The former is a doubtful British species, and the latter is by 

 no means a generally abundant insect with us. During the years 1863 to 1865, the larvae of a 

 Toitrix {Graplwlitlia Pinicolana) increased to such an extent that all the larch forests in the Upper 

 Engadine were stripped of their leaves in July, 1865, and it seemed as if their very existence 

 would be endangered if the larvae continued their ravages for another year. But, numerous as the 

 larvae were, they nearly all sickened, perhaps on account of their food failing them, and either died 

 without becoming pupae, or died in the pupa state, so that very few moths arrived at maturity. 

 Next year there were very few larvae to be seen. For several years previous to 1875, one of the 

 small Ermine Moths {Hyponovieuta Malindla) had been very destructive to the fruit-trees in various 

 parts of France, but in 1875 the larvs of Clisiocampa Ncustria and Liparis Dispar, which appear 

 earlier in the year, were beforehand with it, and stripped the trees of their lca\'es by the time the 

 Hyponoineuta larvae appeared. The latter consequently found no food, and were actually starved 

 out by other larvae, larger and as voracious as themselves. The nature of the injury caused to 

 plants by the larvae of Lcpidoptera depends on the habits of the latter. Some, which feed inside 

 the trunks and roots of trees, impede their growth, and may perhaps cause their death. Among 

 these may be mentioned the larvae of Cossiis Liguipcrda and Zciizcra j^scidi, which are met with in 

 trees of various kinds, and those of Trocliiliiim Apiforinis, and Scsia Myopiforiiiis, and Tipidifonnis, 

 which attack the poplar, apple, and currant respectively. Those which feed on the leaves of trees 

 likewise impede their growth, and often destroy them by continued attacks. Among these we may 

 mention the larvae of the Brown and Gold-tail Moths, the Lackey Moth, the Small Ermine Moths; 

 and on the Continent, those of the Black-veined White Butterfly, as particularly destructive to fruit- 

 trees. Other larvae may be mentioned as only occasionally destructive, such as the White Satin Moth 

 to willows ; Dasycliira Pudibujtda to beech ; the Processionary Caterpillars (on the Continent) to 

 oak and fir ; Fidonia Piniaria to pine ; the green Tortrix to oaks, &c. Much havoc is wrought in 

 our gardens almost every year by the larvae of the WHiite Cabbage Butterflies and of the Cabbage 

 Moths. Many Tortriccs live in and destroy the young shoots of trees, while others live in various 

 fruits and seeds. The larva; of the winter moths, of Eiipithecia Rcctangulata and Laverna Atra, 

 destroy the buds of fruit-trees. The roots of grass and corn are destroyed by many insects, among 

 which are the larvje of the Ghost Moth and of Charceas Graiuiuis. Much mischief is often caused 

 to the Continental vineyards by the larva of Conchylis Rosa-ana, which is double-brooded, and 

 destroys the buds in spring, and the half-ripe grapes in autumn. 



Nor do all Lepidopterous larv;e content themselves with fresh vegetable food. Many of the 

 smaller Lcpidoptera live in our outhouses and storehouses, and their larvae feed on dried products. 



