B.C. Entomological Society. 



held responsible for iniicli of the larch-disease (Dasyscyplia iviUcommU) . Beetles in 

 boring or inserting the ovipositor into the fungus-infested tissue of diseased trees 

 carry the minute ascospores to healthy trees and set up infection there, just as 

 mosquitoes are believed to carry infection from one human being to another. 



Insects produce Malformations. 



Again, the Cccidomyia and other gall-forming insects cause the formation of 

 wonderful and often beautiful structures on the leaves and branches of many of 

 our native plants. This subject is much in need of working-up. What plants do 

 you find galls on? What insect is responsible for each? Does one species of insect 

 produce galls on more than one species of plant? If so, are the resulting malforma- 

 tions similar? It is intere.sting to examine the structure of these galls and note 

 the abnormal growth which has taken place, compared with the natural growth of 

 an unaffected part. It is believed that when the egg is deposited a little fermentive 

 fluid is exuded which stimulates the cells in the immediate neighbourhood to absorb 

 more-nourishment ; this nourishment is absorbed by the young larva, which is capable 

 of stimulating a larger number of cells to ultimately form these curious malforma- 

 tions known as galls. 



Insects destroy much Vegetable Life. 



As to the depredations of the larvse of butterflies and moths, sawflies, etc., the 

 systematic botanist is perhaps not so severe as the economic entomologist. These 

 insects require food, just as our cattle and horses do. Insects may be responsible 

 for the destruction of much vegetable life, but man himself is the greatest of all 

 sinners in this respect. Nevertheless, the botanist is interested in the causes which 

 lead up to these depredations, which come home to him in other ways besides the 

 increased cost of living. 



We find that in nature such depredations leave us with a greater proportion of 

 plants more able to resist attack, and if insects prefer cultivated plants rather than 

 native plants, it is because the cultivated ones are unnatural, abnormal. Indeed, 

 to the systematic botanist, most of our farm and orchard crops are freak specimens, 

 which, on account of their long isolation from their natural environment, are less 

 able to resist the attacks of their natural enemies, and without the aid of man to 

 keep them as they are they would revert to their natural condition, or become 

 exterminated altogether. 



Battle between Plants and Insects. 



All through nature we have this constant battle between plants and insects. 

 It is not a one-sided battle ; sometimes the insects win, and sometimes they lose. 



Insects win. — Most people are familiar with the depredations of caterpillars, and 

 'inany believe that the vegetable kingdom is pretty much at the mercy of the animal 

 kingdom, but this is not so. We are all dependent on the vegetable kingdom, and 

 seeing that* the plant world has supported the population of the animal world for 

 many thousands of years, it is only natural that insects should select the best food 

 they can get from the enormous menu at their disposal. 



Plants icin. — Comparatively few people, however, are familiar with the depreda- 

 tions of plants on insects. Take, for example, the common house-fly. One of the 

 most deadly diseases of this far too common insect is a fungus known as Empusa 

 muscw. In the north of Scotland, where this is common, I have seen within an 

 area of two or three square yards hundreds of dead flies attached to the stems and 

 leaves of small plants such as grasses and shepherd's purse. 



The spores of this fungus are extremely small, and have a viscid coat around 

 them. They are shot off from the ends of minute fungus-threads, and float about 

 readily in the air. If one should come into contact with a fly, it sends a small 

 sucker into its body and gradually begins to grow in the interior of the insect. 

 Finally, the fly becomes weakened, and settles down to rest ; the fungus then pushes 



