THE CELERY LEAF MINER. 9 



soon as the box containing them was opened many flew out of the 

 window. Mr. Theobald remarks that we have no indigenous 

 species with such a ravenous appetite, and if it succeeds in adapt- 

 ing itself to this country, it will form a substantial aid in checking 

 the Hop Aphis. 



The Celery Leaf Miner. 



Acidia hemc/ei. 



This destructive enemy of celery plants was recorded in numerous 

 instances during May and June, and again towards the latter end 

 of the year. In most cases it was found on the celery plant, and 

 not unfrequently where the same kind of crop had been grown 

 year after year. 



THE CELERY LEAF MINER (Acidia lieraclei). 

 Figs. 12 and 13. The fly and larva. (Both greatly enlarged.) 



The fly which is one eighth of an inch long, makes its 

 appearance towards the latter end of April, and the female deposits 

 her eggs, which are numerous, on the upper side of the leaves. 

 These hatch out in about six days time and the larvae at once com- 

 mence to bury themselves in the tissues of the leaf, tunneling them 

 and forming mines. In about a fortnight's time the larva changes 

 to a pupa, inside a pupa case, and sometimes this remains on the 

 leaf, but usually it falls to the ground. After a few days the fly 

 hatches out and the life-cycle is again repeated. The last brood 

 remains in the pupal stage in the earth throughout the winter. 



PREVENTATIVE AND REMEDIAL MEASURES. 



To keep the flies from laying their eggs upon the leaves, dusting 

 the leaves with a mixture of finely powdered soot and lime (3 parts 

 of soot to one of lime), has proved beneficial. It should be used 

 when the leaves are damp. 



When the celery has been dug up, the surrounding soil should 

 be deeply buried, so as to prevent the pupae developing into flies ; 

 while all waste leaves, stems, etc., should be burnt. 



The following sprayflnids have been used with success, 

 especially upon young plants, (i) i quart of paraffin and ^lb. of 

 soft-soap to 10 gallons of water ; (ii) i pint of carbolic acid and 



of soft-soap to 10 gallons of water. 



