66 MEANS FOR ARRESTING THE PROGRESS OF 



shoots in general the temperature should not exceed 130 or 150. 

 It should be remembered that insects, in depositing their eggs, always 

 instinctively make choice of places where the newly-hatched insect 

 will find food without going far in search of it. Hence they seldom 

 lay them on walls, stones, glass, boards, or similar substances ; and 

 therefore the attention of gardeners, when searching for ova, should 

 be directed much more to the plants which nourish the insects, than 

 to the walls or structures which shelter the plants, though it is im- 

 possible to have the latter too clean. 



Collecting or destroying Larvae. Insects in their larva state are much 

 more injurious to plants than they are in any other ; because, as we 

 have already seen, it is in this stage of their transformations that they 

 chiefly feed. With the exception, however, of several of the wingless 

 or crawling insects, and certain bugs and beetles, larvae are in general 

 not difficult to discover, because, for the most part, they live on those 

 parts of plants that are above ground ; but some live on the roots of 

 plants, and these are among the most insidious enemies both of the 

 gardener and the farmer. The ver blanc, or larva of the cockchafer, 

 in France, and that of the wire- worm, in England, are perhaps the 

 most injurious of all underground larvae, and those over which the 

 cultivator has least power. Underground larvae may be partially 

 collected, but not without much care and labour, by placing tempting 

 baits for them in the soil. As they live upon roots, slices of such as 

 are sweeter and more tender may be deposited at different depths 

 and at certain distances, and the places marked ; then, the soil being 

 dug up once a day, the insects may be picked off and the baits re- 

 placed. Slices of carrot, turnip, potato, and apple, form excellent 

 baits for most underground larvae. Such as attack leaves as, for 

 example, those of the gooseberry may be destroyed in immense 

 quantities by gathering the leaves infested by them, as soon as the 

 larvae become distinguishable from the leaf by the naked eye, and 

 sprinklings of hellebore powder will likewise destroy the gooseberry 

 caterpillar. Instead of this being done, however, it too frequently 

 happens that the larvae escape the notice of the gardener till they are 

 nearly full grown, and have done most of the mischief of Avhich they 

 are capable. Hand-picking has been found most serviceable in 

 preventing the injury caused by the black caterpillar on the turnip 

 leaves, which, in certain seasons, has proved destructive of the entire 

 crop. It may also be applied to the destruction of the cabbage cater- 

 pillars. Here, also, we may notice the beneficial effects of picking 

 out and destroying young onion plants infested by the grub of the 

 onion-fly. This ought to be done as soon as the plants appear sickly, 

 because the grubs arrive at maturity in a very short time ; and, by 

 destroying the plant, future generations of the fly are prevented. 

 Grub-eaten fruit ought also to be picked up as soon as it falls to the 

 ground, before the enclosed grub has time to make its escape into the 

 earth, and which it would do in a very short time, the fruit not falling 

 until the grub has arrived at its full size. The larvae of some kinds 

 of saw-flies envelop themselves in a kind of web in the day-time, and 



