438 Insects most injurious to Cultivators. 



branch. He thinks it probable that they may derive some little 

 support from the sap of the branch under the shell or covering 

 where they reside ; but it is quite clear that they never emerge 

 from their birthplace to obtain food, or form any additional re- 

 sidence, till they are influenced by the warmth in the following 

 spring: — Mr. Lewis takes up the observation where it had been 

 left by Mr. Major, and states that, about the time that the trees 

 are coming into leaf, the caterpillars make their escape; but they 

 do not commence spinning webs immediately : they cannot yet eat 

 the epidermis of the leaves, and they require some protection 

 from the cold and rain, which their tender frames are not yet 

 fitted to endure: to effect this they mine into the leaves, eating 

 the cellular tissue only, and leaving the epidermis untouched. 

 Having acquired sufficient strength to withstand the vicissitudes 

 of the atmosphere, and to devour the epidermis of the leaves, 

 they make their way out ; and the anxious gardener, who has 

 hitherto only observed the brownness of the leaves caused by the 

 mining, but which is by him attributed to the withering blast 

 of an easterly wind, is astonished when he perceives myriads of 

 caterpillars swarming on his trees, and proceeding with alarming 

 rapidity in their devastating course. The fact of their mining 

 sufficiently exjilains the reason of their sudden appearance: it 

 shows how one day not a single caterpillar may be visible on the 

 trees, and the next they may be swarming with larvae, of so 

 large a size as to rebut the idea of their having been recently 

 hatched. 



For the destruction of these insects, various plans have been 

 recommended. Mr. Major says that nothing more is required 

 than the application of strong soapsuds forcibly applied with 

 the engine, so as to break the web, that the suds may reach the 

 insects. Where the trees are not much infested, gather the webs 

 including the caterpillars, by hand, and destroy them in any way 

 most convenient. Care should, however, in these cases, be 

 taken to kill, and not merely to disturb, the caterpillars. Mr. 

 Lewis suggests the picking off and burning of the leaves whilst 

 the caterpillars are in the mining state; the presence of the 

 insects being indicated by the blighted outward appearance of 

 the leaf: but prevention is always better than cure, and it seems 

 to me easier, as well as more advantageous, to destroy the moths 

 as soon as they are produced, and before they have had time to 

 deposit their eggs. The generally simultaneous appearance of 

 the entire brood in the winged state, together with the very con- 

 spicuous appearance of the moth, will render this a matter of 

 great facility. A sheet may be laid beneath the branches in the 

 daytime, which should then be sharply struck with a stick; when 

 the moths, which at that time are sluggish, will fall into the sheet, 



