Insect Pests and Fungoid Diseases. 421 



CELERY AND PARSNIP FLY (Acidia heraclei).Thc Celery Fly 

 makes its first appearance in April. It is a small fly, about one-eighth of 

 an inch in length with a wing expanse of nearly half an inch ; tawny brown 

 body with a lighter colour underneath. The eyes are deep green and the 

 legs dark yellow. The wings are transparent with dark brown markings. 

 The eggs are laid singly on the upper surface of celery and parsnip leaves ; 

 these hatch out in about six days and the larvae or grubs immediately burrow 

 between the upper and lower epidermis of the leaves, eating the green 



1, Fly, magnified; 2, Larva, magnified (lines show natural size of each); 

 3, Pupa, natural size. 



tissues and doing much damage by checking the growth of the plants. 

 Celery subjected to a bad attack is stunted, will not blanch properly, and is 

 bitter in flavour, whilst parsnips come small and of a bad shape. The 

 grubs change into papa in about fourteen days, sometimes remaining in the 

 leaf and sometimes falling to tne ground. From these, flies hatch out 

 in about six days and another attack begins, and so one brood follows 

 another through the summer, and when the weather is mild the pest con- 

 tinues until late in autumn. 



Treatment : Where celery is grown extensively the wisest plan is to 

 take measures to prevent an attack. To this end, whilst the plants are 

 young they should be sprayed two or three times with paraffin emulsion, or 

 they may be dusted occasionally whilst the leaves are wet with a mixture 

 of equal parts of slaked lime and soot, though probably the spraying would 

 be most effective. 



Where preventive measures are not adopted a sharp look-out should be 

 kept for evidence of the fly. All infested portions of leaves should be picked 

 off and burnt until no trace of the grub is seen, then the plants should be at 

 once sprayed or dusted as indicated above. It is important that the first 

 brood should be thoroughly dealt with, and then the chances of attack by 

 later broods will be considerably lessened, and probably avoided altogether. 

 Where there has been a bad attack the plants should receive a moderate 

 dressing of nitrate of soda mixed with a little agricultural salt, followed by 

 copious waterings ; this will force rapid growth and enable the plants to 

 grow away from the pest, besides repairing any damage it may have done. 



MUSHROOM PEST (Scmra ingenua). Mushroom beds, especially 

 those under cover, are often infested with these active little insects, which 

 are often present in great numbers, and do a great deal of damage by 

 eating the inner part of the fungi and leaving only the outer shell. 



