GARDEN PESTS 69 



dark greenish insect about I inch long, which appears 

 in spring and plays havoc in bad seasons with both carrots 

 and parsnips. The female lays her eggs on the crown of 

 the young root, especially favouring the time when the 

 soil is opened out by thinning. It is beheved that the 

 scent of the carrot attracts the fly more then. Probably 

 this is from the bruising of the roots, and it is therefore 

 advisable to thin early and all at once, and hurry the 

 crop, as each time it is done may bring a fresh visitation. 

 Trenching will expose pupae to the elements, and gas- 

 Hming in winter is also good. (See Plate 15.) 



Allotment-holders in and around London had cause 

 last year to remember the Onion Fly, as a great portion 

 of the crop was spoiled. This is a dipterous insect, 

 resembUng a house-fly, grey in colour with brownish 

 stripes on the thorax and nearly | inch across the 

 wings. The eggs are laid either on the neck of the onion 

 or on the soil close by. The maggots burrow down and 

 feed on the bulb. Soil spray with paraffin emulsion and 

 soot dressing are applied, but they must be constantly 

 renewed after wet. Firmness of soil and earthing the 

 onions up to the neck in the early stages are great mechani- 

 cal aids. Small birds like the wren are useful as natural 

 foes of the onion fly. The scientific name is C. cepeio- 

 rum. (See Plate 16.) 



Another small diptera is the Celery Fly {T. onopor- 

 dinis), a dark-winged insect measuring shghtly more than 

 the preceding example, which lays its eggs in the middle 

 of May on the green leaves of the plant, where a swollen 

 blister presently shows the existence of a fly maggot. 

 These should be pinched out, care being taken not to 

 split the leaf. If any leaves are removed they should be 

 burnt. The pupse in the soil should be exposed to the 

 birds, starlings being very fond of them. Trenching is 

 said to bury the pupse too deep for them to find their way 

 out again. (See Plate 16.) 



As aheady stated, the Carrot Fly also attacks Parsnip. 



