158 ONION. 



Up to the year 1882, as far as I am aware, the injury to the 

 Onion crops in this country was commonly supposed to be 

 caused by only one kind of Onion Fly, but in the course of 

 that year specimens of maggots infesting Onions in various 

 localities were sent to Mr. R. H. Meade, of Bradford, from 

 which he reared another species, the Antltomyia lylatura of 

 Meigen, sometimes known on the Continent of Europe as the 

 Shallot Fly. 



These two species were very much alike in appearance, but 

 do not seem to be quite similar in position of egg-laying, 

 which is important practically. 



From the observations I had the opportunity of making 

 carefully in my own garden, I found attack was generally 

 begun, not by deposit of eggs on the leafage, from which eggs 

 the maggots might eat their way down into the bulb, but from 

 eggs laid either quite at the base of the bulb, or at the lower 

 part of the side. I submitted some of these maggots to 

 Mr. R. H. Meade, and results showed that they were larvae, 

 not of the Phorhia cepetorum but of the A. platura, otherwise 

 the Shallot Fly. 



The kind of attack does not appear to depend on the age of 

 the Onion, as in the case of maggots forwarded by Mr. 

 Malcolm Dunn, which were attacking Onions at Dalkeith 

 whilst still so young that hardly any bulb was formed ; these 

 were found in due course, by Mr. Meade, to be of both of the 

 above-named kinds. As shown further on, knowledge of the 

 habit of attacking the bulb may be most serviceably made 

 use of in preventing attack. 



Peevention and Remedy. — One of the first points to be 

 attended to is cleaning the ground from infestation. 



The pupa or chrysalis of the autumn brood remains in the 

 ground, or sometimes in decayed Onions, during winter, and 

 the fly comes out from it in time to attack the young Spring 

 Onions ; therefore Onions should not be grown two years 

 running on the same ground. It has been observed that the 

 fly, when buried a few inches deep, has much difficulty in 

 coming up through the ground if it is at all firm. For this 

 reason, when Onion-beds have been much infested, it is a good 

 plan to deeply trench the ground, turning the top spit into the 

 bottom of the trench. By this means the fiy-cases are 

 buried so deep that the flies cannot come up from them, and 

 also the cases are not brought up to the surface again by the 

 common routine of digging or cultivation ; it would probably 

 answer every purpose, as far as keeping the fly from coming 

 up is concerned, if the surface was simply turned down one 

 spit deep ; but it should always be borne in mind that the 



