38 ENTOMOLOGICAL SOCIETY OF ONTARIO. 



Some species are injurious in one stage of their existence and useful at another. 



Our Hawk-Moths by dispersing pollen act beneficially for the fertilization of 

 blossoms ; but if unchecked increase were allowed them, their caterpillars would become 

 terrible pests, and would destroy not only our fruit-trees but many of our shade and 

 ornamental trees also. Their numbers are however kept down by various species of 

 ichneumons belonging to the genera Ophion, Cryptus, Microgaster, Apanteles, etc. I 

 have seen as many as 150 parasitic grubs issue from one larva of Sphinx lialmioe, A. tfc S. 

 It can easily be conceived that foes so numerous and so deadly would soon exterminate 

 the Sphinges altogether.* 



This would be a pity for, as I have said, the moths of the family perform a useful 

 part. They are moreover very beautiful, and 



" A thing of beauty is a joy forever." — Keats. 



But the checks are met by counter-checks. Of those 150 grub3 that I have mentioned 

 not more than two or three escaped the attacks of a secondary parasite, Pteromalus 

 tabacum, Fitch. This last named insect is a brilliant little object that once seen can 

 hardly be forgotten. 



People are familiar with the idea of one grub feeding inside another grub ; but it is 

 not so generally known that there are insects that pass their early stages and attain perfec- 

 tion inside the eggs of other insects. Ashmead in his valuable work on the Proctotry- 

 pidse, published in 1893 by the Smithsonian Institution, has given descriptions of forty-one 

 such insects. 



Then there are numerous kinds of ground-beetles, lady-birds, syrphus- flies, soldier- 

 flies, dragon-flies, etc., predaceous on other sorts, and therefore beneficial to man. 



The first point I make then is this : — A knowledge of Entomology is important that 

 men may rightly distinguish between their insect friends and their insect foes. 



In a paper which I had the honour to read before the Fruit Growers' Convention 

 at Ottawa, I showed the important work done by Humble Bees in the cross fertilization of 

 blossoms. These insects are so entirely beneficial that some of their kind have been — 

 with a sort of grim propriety — transported to New Zealand to labour there for the public 

 good. 



But, at the very time that the Humble . Bees are operating in the orchard for the 

 fruit grower's benefit, there are a number of other insects at work that do a vast amount 

 of harm, namely, the Bud-worms, Canker-worms, Leaf-rollers, etc. The great remedy 

 against all these hurtful insects is arsenical spraying. But if this spraying be delayed till 

 the blossoms are opened the nectaries will become clogged with the arsenite, and though 

 the instinct of the bees may lead them to shun the poisoned ^blossoms, the good those 

 insects would do will be left undone. The first spraying should be given before the flower- 

 buds are opened ; the second after the fruit is fairly set. 



The Ontario Legislature passed a law in April, 1890, which says : 



"Sec. 1. No person in spraying or sprinkling fruit trees during the period within 

 which such trees are in full bloom shall use, or cause to be used, any mixture containing 

 Paris green, or any other poisonous substance injurious to bees." 



Promptitude in dealing with in urious insects is always of the utmost importance. 



A patch of aphides neglected will spread, and spread, till it covers a tree — a little 

 one becoming a thousand. 



The apple tree Aphis (Aphis mali, Fab.) lays its eggs in the fall ; and Mr. F. M. 

 Webster suggests that apple trees should be sprayed in winter (see 24th Rep. of the Ent. 



* Let us suppose that the whole number of grubs mentioned would produce perfect insects, and that 

 half of these would be females ; then let us see what the natural and uuchecked increase of these would be 

 at the end of five years. A little figuring will shew that it would amount to the enormous number of 

 4,746,093,750. 



