CH, IX PESTS 161 
when present, and there will not, [ think, be much 
trouble about their identification. 
The keeping the plants in vigorous health is the 
first preventive measure, for it seems undoubted that 
aphides, the scale insect, and red spider show a 
partiality in their attacks for plants which are in a 
weak and sickly condition. Against all caterpillar 
and grub depredations, late pruning, after the plants 
have burst into leaf, is the only prevention that I 
know of : when this measure has been found necessary 
through the earliness of the season, a considerable 
diminution is found in caterpillar numbers ; and it is 
plain that in such cases the parent insects have laid 
their eggs on the bursting buds at the top of the 
shoots, and that all have been happily swept away at 
the pruning. 
I was surprised on first looking into the matter to 
find that most of the common caterpillars or grubs 
which haunt and injure the Rose are the larve of 
moths. We sometimes see a good many flies of 
different sorts and sizes about our Rose shoots on 
sunny days in April and May, but rarely moths, 
though there may be, later on, several moth grubs 
on every plant. The reason of this would probably 
be that the parent moths visit the plants only at 
night or at all events in the dusk, and that they are 
mostly small, insignificant, fluttering insects of the 
most harmless appearance, and likely in general to be 
unnoticed. 
Among the flies we may perhaps notice some active 
creatures, less than half an inch long, looking some- 
thing like slender-bodied long-legged ants, with 
iridescent wings; these will be saw-flies, the parents 
of very hurtful grubs, and each one caught will 
M 
