9. APPLE, 
they spin a cocoon or web covering, in which they go through their 
changes; whilst, on the contrary, the caterpillars of the Apple Sawfly 
go down into the ground, and there, at a depth of two, three, or four 
inches (or even, if the soil is very friable, at a depth of seven inches), 
they form their cocoons, from which the Sawfly comes out at the time 
of the Apple flowers in the following season. 
Consequently on this difference in habits, much good time and 
labour is apt to be more than thrown away in scraping and dressing 
the Apple tree trunks to get rid of Codlin Moth infestation, whilst all 
the while the caterpillars of the less known Apple Sawfly infestation 
may be lying unharmed close by beneath the surface of the ground 
ready to develop and start new attack with the opening of the next 
season’s Apple blossoms. 
The caterpillars of each of the above kinds are so far similar 
both in size and shape that, without careful examination through a 
magnifying-glass, it is very easy to mistake one for the other; but, 
when closely examined, it will be seen that the caterpillar of the 
Codlin Moth has four pairs of sucker-feet beneath the body, whilst the 
caterpillar of the Apple Sawfly has sia pairs. By this difference in the 
number of the sucker-feet, and also by a very disagreeable scent, much 
like that of a plant-bug, or of a common bed-bug, the caterpillar of 
the Apple Sawfly may be distinguished from that of the Codlin Moth. 
The history of both of the above infestations has been given at 
length in my Annual Reports,* but the following notes of the chief 
points are now given together for convenience of comparison where 
there is doubt as to which of the attacks is present. 
The main points of the history of the Codlin Moth infestation are 
as follows. The moths come out about the time of the opening of the 
Apple blossoms, and when the blossom-leaves have fallen and the fruit 
is beginning to set, the moth lays her egg at the eye of the little Apple 
(that is, at the end opposite the stalk). Commonly only one egg is 
laid, but sometimes two or three may be laid; and also they may 
sometimes be laid by the stem of the young Apple, or on the cheek. 
The maggot hatches in about a week or ten days, and gnaws its 
way into the Apple, where its presence is shown by the dirt thrown 
out at the eye of the Apple, or at the opening of a passage gnawed by 
the grub through the young fruit to enable it to throw the pellets of 
dirt out which could not be got rid of by forcing them through the 
small entrance burrow. It then feeds in the centre of the fruit, 
piercing the core, and injuring the ‘ pips,” and consequently the 
Apple falls. This is about four weeks after the maggot has hatched. 
If the maggot is still in the fruit when it falls, it leaves the Apple and 
* For Codlin Moth, see ‘ Twentieth Annual Report,’ pp. 1-9; for Apple Sawfly, 
‘Fifteenth Report,’ pp. 1-5, and ‘ Sixteenth Report,’ pp. 10-17. 
