PREVENTION AND DESTRUCTION OF INSECT PESTS. 489 



let us see -where insects generally take up their winter quarters. 

 After an attack of onion maggot, rust, celery fly, cabbage maggots, 

 and wurzel fly, &c. (all of which are the larvae of Diptera), we shall 

 find in the ground during the winter numberless small, oval, brown 

 bodies known as " puparia," each of which contains a pupa derived 

 from one of the maggots. We must not forget, however, that some 

 of the larvae have not matured by the time the crop was lifted, and 

 thus some are harvested with the crop, as we find in maggoty 

 onions and rusty carrots ; or they may remain in the leaves, as in 

 the case of celery-fly, or in the rotting stalks and roots, as in cabbage 

 maggots. Now, if these are left in and on the ground and not 

 destroyed, fresh generations appear next year, and should a similar 

 crop be grown on or near the same land it stands a considerable 

 risk of further attack. Again, in savijiy larvce attack on fruit-trees, 

 at the end of the year the larvae fall to the ground, bury themselves 

 a few inches beneath the bushes and trees, and forming a case 

 of silk and earth, likewise pupate. They often remain as larvae 

 in the cocoon until the spring, and then pupate. A very large 

 number of moths also are found in the pupal stage in the earth 

 in the winter time. At this time of year one and all should be 

 destroyed. Two methods seem to recommend themselves — one, 

 turning over the land so as to expose the pupae to the attack of 

 birds, which greedily devour them ; another, by dressing the land 

 with some such substance as fresh gas-lime, which is one of the 

 best winter insecticides to use when we can let the land rest. After 

 a bad attack of currant sawfly, we may remove the soil from beneath 

 the currant and gooseberry bushes in winter and burn it. 



It must he remembered that frost has little or no injwrious effect 

 upon insects in the egg or pupal state, or even upon most maggots. — 

 I have known chrysalids frozen as brittle as glass, and yet their 

 vitality was unimpaired. Frost, if anything, is beneficial to insect 

 life, for the hard state of the ground protects the creatures from the 

 attack of birds. Many insects hibernate in the adult state, — such 

 as the turnip-flea, thrips, pea- weevils, apple-blossom weevil, earwigs, 

 &c., — taking refuge in hedgerows, grassy headlands, rubbish-heaps, 

 and so forth. Hedges bordering fields and gardens, and all grassy 

 patches, should be well cleaned in the winter, the material burnt, 

 and all rubbish cleared off and similarly destroyed. The dead 

 leaves that coUect in currant-bushes harbour the young larvae of the 

 currant moth {Abraxas grossulariatd), and should therefore be cleaned 

 oxit. All pni/nings of fr-uit-trees should be burnt, and not left about in 



