52 EXPERIMENTAL FARMS 



9-10 EDWARD VI!., A. 1910 



so that the numbers of the plant lice may be reduced before serious injury is done 

 to the grain plants.' 



In 1908 it was noticed, in many places, that towards the end of the season, the 

 parasites were present in large numbers and were quickly reducing the colonies of 

 the aphis, but some reports say that they did not appear soon enough to prevent some 

 damage. 



The Clover-seed Midge, Cecidomyia leguminicola Lint. — During the past season 

 the Clover-seed Midge has done serious damage in districts in Ontario, where clover 

 is grown for seed. Many complaints have been received from farmers of the presence 

 of the small, legless, pink maggots in their clover seed at threshing time, and some 

 anxiety has been felt as to whether these would mature, and affect the crop of next 

 year. In the samples received at the Central Experimental Farm, all the maggots 

 were dead and shrivelled up. 



The life-history and habits of this insect are well known. There are two broods 

 in the season, corresponding with the two crops of clover seed. The eggs are laid in the 

 forming flower heads of the clover; when these eggs hatch, the maggots penetrate the 

 seed pods and destroy the seed. When the larvae are full grown, about the end of 

 June, they leave the clover-heads and enter a short distance into the ground, to 

 change to pupae. The perfect insects, forming the second brood, emerge from the 

 ground, just as soon as the second crop of clover is coming into flower, and the females 

 at once begin to lay their eggs amongst the forming blossoms. These eggs soon hatch, 

 and about the time the seed is ripe the maggots leave the clover and enter the ground 

 to pass the winter, whence they emerge again the next spring, just at the time the 

 clover comes into flower. 



Experience has taught farmers that the practice of feeding off their clover fields 

 with cattle and sheep, until the beginning or middle of June, or cutting it before the 

 20th of that month, is the only way to secure an autumn crop of seed; thus the 

 maggots of this first brood are destroyed by the cattle eating them, or they dry up 

 with the clover hay which has been cut before they were mature enough to leave tbe 

 heads of clover and go into the ground to pupate and change to the perfect insect, 

 which is a small midge. If the clover is left standing in the fields till the end of 

 June, a sufficient time elapses for this latter process to take place, and the perfect 

 flies emerge again just in time to lay their eggs in the opening flowers of the second 

 crop. In this way the seed of the second crop is destroyed, as well as that of tbe first. 



As mentioned above, in all the samples of clover seed received last autumn and 

 during early winter, the maggots were already dead and dried up; consequently there 

 would be no advantage in destroying, by burning, such material. At threshing time, 

 however, if the living maggots are noticed, it would be a good practice to have all 

 screenings swept up and burned. 



The Hop Flea-beetle, Psylliodes punctulata Melsh. — This insect in 1908 again 

 did extensive injury to the hop plants in the large yards in British Columbia. During 

 the last three years it has been estimated that this small black flea-beetle has destroyed 

 fully three-fourths of the hops grown in British Columbia, 



The following letters from the correspondence received by the late Dr. Fletcher 

 show how extensive this outbreak was in 1908, in the large hop yards of Sir Arthur 

 Stepney, at Agassiz, B.C.: — 



1 Vancouver, B.C., April 23. — The flea-beetles since my last visit (to Agassiz) 

 two weeks ago have appeared in large numbers, and are now destroying the shoots of 

 vines which are some five or six inches high. They are also in considerable numbers 

 in the poles. Mr. Wilson showed me your letter to him, advising the spray of whale- 

 oil soap, one pound in ten gallons of water. Fortunately we had a considerable supply 

 of this on hand, and I immediately tried the solution advised by you, with most 

 gratifying results. Outside of kerosene it is the only thing we have found so far that 



