731 
Annual Report for 1891 of the Zoologist. 
to be Pterostichus madidus, TIar pains ruficornis, and Calathus 
cisteloides. Unfortunately, when the case was reported the attack 
was already over, and it was too late to make any inquiry into the 
facts. 
There are many possible sources of error in the observations. 
The beetles in question are very common, and would be much more 
conspicuous than the strawberry weevil, for example ( Otiorhynchus 
sulcatus), which may possibly have been the true culprit. Again, 
the ground beetles may have attacked the strawberries, but only 
such as contained minute larvae, which were the real objects of their 
search. 
If these beetles are really injurious, it is hard to understand how 
any strawberry crop can escape a pest which is always present in 
such large numbers. 
Tiie Oak Tortrix. 
Tortrix viridana. 
This pest occurred in vast numbers last June in the South of 
England, and its caterpillars entirely stripped the oak-trees in 
Windsor Forest. It is very erratic in its occurrence, often being 
scarcely discoverable where it abounded the previous year. This 
sudden disappearance is, no doubt, due to the immense increase, 
during the year of its abundance, of the insects which prey upon it. 
Unfortunately, on account of the impossibility of predicting a 
serious attack, and of the very large area generally involved, it seems 
impossible to suggest any practical method of combating it. It does 
not, luckily, do much permanent harm. 
The oak has great powers of recuperation, and will generally put 
forth a second leafage, and I am not aware that it ever actually 
succumbs to this pest, though it may undergo some amount of dis- 
figurement. Many birds prey upon the caterpillars, including the 
common house-sparrow. Lord Vernon has suggested that this fact 
might be utilised, and considerable numbers of sparrows introduced 
into an infested district. The experiment is worth a trial when the 
caterpillar begins to be troublesome, though it is exceedingly doubt- 
ful whether the birds would remain in the woods. 
Miscellaneous. 
Amon» other pests about which inquiry has been received, but 
which do not call for any special report, are clover weevil, strawberry 
weevil, turnip-gall weevil, red spider, snowy fly, goat moth, red 
maggot, root maggots, celery fly, -various aphides, pear sawfly, and 
several species of caterpillars. 
In March a correspondent recommended formic aldehyde as an 
insecticide especially suitable for greenhouse use, but careful experi- 
ments made with this substance on various infested hothouse plants 
do not appear to justify the adoption of the treatment. 
Cecil Warburton. 
Zoological Laboratory, Cambridge. 
