34 ENTOMOLOGICAL SOCIETY OF ONTARIO. 



0. llymenoptcra. — Vespa (wasps) (Fig. 39) ; Chry&is (cuckoo flies), Ichneumons, 

 (Fig. 40). 



Fig. 39. Fig. 40. 



The above insects are of great importance in keeping the injurious insects upon 

 which they prey in check. The ichneumons are most valuable in this respect. They are 

 very numerous, and prey on many injurious insects, by depositing eggs in the larval 

 forms. These eggs give rise to larval ichneumons that feed upon their host, which 

 finally dies. About this time the ichneumons are developed and escape as perfect insects. 

 The lady birds are destroyers of plant lice ; ground beetles prey on the potato beetle 

 and several caterpillars, and the tiger beetles are great devourers of several species of 

 insects. 



(d) Plants. Some plants in the lowest orders do good service in destroying insects 

 by being parasitic. Some (Empusa) attack the flies in autumn ; some (Sporotrichum) the 

 dreaded chinch bug, which is sometimes a serious pest in variou3 parts of the United 

 States ; while the white grub has among its destroyers the parasitic fungu3 Cordyceps. 



2. Insecticides (substances used for killing insects'), Gas, Paris Green and Kerosene 



Emulsion . 



Poisonous gas, generated in tents placed over shrubs and trees affected by scale 

 insects, etc. 



Carbon Bisulphide. — This colourless liquid is a most eSectual remedy to get rid of 

 insects in granaries, but great care requires to be taken as it is very inflammable and 

 explosive, and may lead to serious results if any fire is brought near ; even a cigar or 

 pipe used where the vapor is being evolved may prove disastrous. It readily volatilizes ; 

 the vapor is heavier than air and is deadly to insect life. In using it the liquid may be 

 placed in a small shallow vessel and put on the top of the grain, in bins or barrels. 

 These are covered so as to keep in the vapor, which sinks down through the grain, destroy- 

 ing insect life wherever it comes in contact with it. After the operation is over the 

 grain will lose all odor in a short time if exposed to the air. Some prefer taking a wad 

 of cotton or tow, saturating it with the liquid, then plunging it into the middle of the 

 bin and leaving it. Two or three bunches thus placed among the grain will soon kill all 

 such pests as are found in it. One ounce is about sufficient for two bushels of grain. 



Paris Green. — (Arsenite of copper, containing 50 -60 per cent, of arsenic.) This is 

 applied dry or in solution. In the dry form it should be mixed with 50 to 100 parts of 

 plaster, wood ashes, flour or air -slacked lime and du3ted upon the affected plants. The 

 form in solution is usually one pound of Paris green to 200 gallons of water ; but if the 

 foilage is tender, 250 to 300 gallons of water may be used. This is the usual strength 

 applied*upon the plum and peach. As the green powder does not dissolve it requires to 

 be kept thoroughly mixed by constant stirring. One pound of lime to every 100 gallons 

 will prevent injury to the foliage. The Paris green should be first made into a thin paste, 

 in a small quantity of water, and then added to the full amount of water. 



Kerosene Emulsion. — This is a mixture of coal oil and water. 



