DESTRUCTION CAUSED THEREBY TO WOODS AXD TREES. 87 



larch was sold at from Is. 2d. and Is. 3d. per cubic foot, but 

 since the gale it will not fetch Is. for the same quality ; and 

 as no large quantity can be disposed of readily, as larch will 

 keep without deterioration, many proprietors are accordingly 

 holding on their stocks. Spruce, which was before the gale 

 sold at from 5d. to 6d. per cubic foot, cannot be sold now for 

 more than from 3d. to 4d., and frequently for only 2d. per cubic 

 foot, so much has the value of timber fallen, by the enormous 

 quantity thrown upon the markets from the effect of this disas- 

 trous and ever memorable storm of 28th December 1879. 



INSECTS WHICH PREY UPON AGRICULTURAL PLANTS. 

 Ey Primrose M'Conxell, Agricultural and Veterinary College, Glasgow. 



[Premium — Fifteen Sovereigns.'] 



Insects are one great source of loss and annoyance to farmers, 

 and, Rs a general rule, there is no subject which is less studied 

 and understood by them. In the following report it is proposed 

 to describe the life-history of the most prominent of them, and 

 also the means, if any, of coping with them. 



It is advisable to take the various orders and describe those 

 in each order which fall within our limits as the best method of 

 classification, for the reason that the same insect, or an allied 

 species, sometimes affects more than one kind of crop. 



A typical insect passes througli four stages in the course of 

 its life. First, there is the egg — the majority of insects being 

 oviparous ; second, the caterpillar, larva, grub, maggot, or 

 " worm," as they are variously called ; next, the chrysalis or pupa ; 

 and last, the imago or perfect winged insect. Some, how- 

 ever, do not pass through any metamorphosis, while others again 

 are only partially metamorphosed, and they have accordingly 

 been divided into the three great sub-classes of Aiiidahola, 

 Hcmimctahola , and Jlolomdahola. The greatest damage, as a 

 rule, is done by them in the caterpillar or grub stage, thougli 

 there are many exceptions, as for instance, the " turnip liy," 

 which works the greatest mischief as a perfect beetle. 



Taking the sub-classes as they come, we find that there are 

 none occurring under the Amdahola. Tlie others are classitied 

 as follows : — 



HKMLMETAliULA. IIOLOMETAIJOLA. 



Order 1 . II E M i p T E r a. Order ?>. D i p T E R A. 



Sub-order, («) IIoMOPTEKA. „ 4. L E p i DO pteua. 



{h) HeTEROPTEP.A. „ 5. II Y M E N P T E R A. 



Order L\ Xeurqptera. .. t). Coleoptera. 



