INSECTS, OR DESTROYING THEM. 309 



details till particular insects come to be mentioned, when treating on the 

 culture of the plants which they attack. We shall commence with opera- 

 tions connected with the perfect insect, and take in succession the eggs, the 

 larvae, and the pupae. 



353. Deterring the Perfect Insect. The perfect winged insect may, in some 

 cases, be deterred from approaching plants by covering them with netting or 

 gauze, the meshes of which are sufficiently small to exclude the insect, but 

 not too small to prove injurious to the plant by excluding light and air. Wasps 

 and flies are in this manner excluded from vineries and peach-houses while 

 the fruit is ripening. Bunches of grapes against the open wall are also 

 protected by putting them in bags of woollen netting or gauze. Choice 

 plants in pots are sometimes protected from wingless insects by placing the 

 pot containing the plant in the midst of a saucer which surrounds the pot 

 with water, which it is found the insect will not cross. The stems of plants, 

 such as dahlias and gooseberries, are sometimes protected by a zone of 

 glutinous matter, on wool, tow, or paper, over which the insect will not 

 venture. A remarkable mode of deterring some insects from entering houses 

 by the windows is described hi the Architectural Magazine, vol. ii., as 

 practised in Italy, and known even in the time of Herodotus. This is 

 simply to place before the openings of the window a net of white or light- 

 coloured thread, the meshes of which may be an inch or more in diameter. 

 The flies seem to be deterred from entering through the meshes from some 

 inexplicable dread of venturing within. If small nails be fixed all round 

 the window-frame at the distance of about an inch from each other, and 

 thread be then stretched across both vertically and horizontally, the network 

 so produced will be equally effectual in excluding the flies. It is essential, 

 however, that the light should enter the room on one side of it onty ; for if 

 there be a thorough light either from an opposite or side window, the flies 

 pass through the net without scruple. (W. Spence in Transact. EntomoL 

 Society, vol. i.) It would appear to be a general principle, that winged 

 insects may be deterred by meshes of such a size as will not admit them 

 with their wings expanded, and also that insects will not enter from bright 

 light into darkness, more especially if deterred by the slightest obstacle, such 

 as the threads stretched across before large openings in Italy. 



354. Preventing the Perfect Insect from laying its Eggs. Insects may 

 be prevented from laying their eggs on plants within reach by surrounding 

 them with a netting or other screen ; or, in some cases, by sprinkling the 

 plant with some liquid containing a very offensive odour. Thus moths are 

 prevented from laying their eggs on gooseberry-bushes by hanging among 

 them rags dipped in gunpowder and tar ; and probably there are various 

 cheap liquids that might be used in the case of fruit-trees, and perhaps even 

 forest-trees, and possibly for deterring butterflies from depositing their ova 

 on the cabbage tribe. Insects which deposit their eggs in the soil cannot 

 easily do so when the soil is very hard, and may therefore be enticed to depo- 

 sit them in portions of soil made soft on purpose. Thus boxes or large pots 

 filled with rotten tan, sunk in the soil, form an excellent nidus for the eggs 

 of the cockchafer, and will prevent that insect from laying them in the com- 

 mon soil of a garden. Hoeing or digging patches of soil here and there 

 throughout the garden or plantation will have a similar effect, to a certain 

 extent ; and after some weeks, when the larvae are some lines in length, 

 the soil may be sifted, and the insects taken out and destroyed. While 



