78 WILLIAM SAUNDERS ON THE INTRODUCTION AND 
The codling moth (Carpocapsa pomonella), the great scourge of the apple-grower, was 
brought here about the beginning of the present century, and during the comparatively 
brief period which has since elapsed has spread over the greater portion of the North 
American continent. It is abundant and very destructive throughout the greater portion 
of our own country, exists throughout the Northern, Middle and Western States, and of 
late has found its way to the Pacific Slope, where it is committing great havoc among the 
apple and pear crops of that fine fruit region. 
Among the other uninvited immigrants from Europe, in this department, the following 
are worthy of mention: the grain weevil, (Sitophilus granarws), the meal worm (Tenebrio molitor), 
the bark louse of the apple (Aspidistus conchiformis), the gooseberry sawfly (Nematus ventricosus), 
the currant borer (Egeriatipuliformis), and the asparagus beetle (Crioceris asparagi) ; and there are 
many others of less note. All these have now become widely disseminated and, in their 
several spheres of operation, impose upon our farmers, gardeners and fruit-growers a heavy 
yearly tax in time and money, in the efforts necessary to keep them in subjection. 
If Canada has provided a port of entry for several of these pests which have since 
invaded our neighbours adjoining, we in turn have been supplied by them with the 
Colorado potato beetle (Doryphora decemlineata), which has migrated from its former quiet 
home in the cañons of the Rocky Mountains and, fired with the spirit of progress so char- 
acteristic of the United States, has availed itself of all the advantages of transport which 
an advanced civilization affords and thus spread rapidly over the greater portion of the 
continent. 
The manner in which many of these pests have been introduced is not difficult to 
account for. The larve of the wheat midge lie dormant for months in the dry wheat 
heads, or amongst the grain when not properly cleaned, and during this inactive period 
may be carried with the grain many thousands of miles. The Hessian fly passes a long 
period of inactivity lodged in the wheat straw. The second brood of the codling worms 
remains in the winter apples as larvae, or about the apple barrels as chrysalids throughout 
the winter, and thus abundant opportunity is afforded for its distribution. These are given 
as examples, but many other similar instances might be cited. 
With the onward march of civilization, the opening up of new portions of the country 
for settlement and the many means of rapid transit from one point to another, unlimited 
facilities are afforded for the dissemination of destructive insects. An insect on the 
Atlantic coast may take shelter in a railway car for a single night and the next day be 
found hundreds of miles in the interior. It was thus with the Colorado potato beetle and, 
within a short time after it invaded Ontario, it was found in Quebec and Nova Scotia. 
Many species are strong on the wing and able to fly long distances; in this way the 
cabbage butterfly has mainly spread itself. 
Among the methods suggested for the subduing of injurious insects, there are none 
which offer so great a prospect of success as the encouragement and protection of those 
insects which feed on other insects, such as the lady-birds, ground beetles, tiger beetles, 
ete, and more especially by the introduction of those useful parasitic insects which in 
their native homes are always attendant on these destructive species and keep them within 
due bounds. In Europe, although the wheat midge is indigenous, it is rarely very des- 
tructive for the reason that there are three distinct species of minute parasitic flies which 
