Piophila Apii
(Celery-stem Fly). A fly which has been described by Professor Westwood, in the "Gardeners' Chronicle," as injurious to Celery. The yellowish-white maggots burrow, during winter and spring, in the stems, eating their way upwards, and leaving burrows of a rusty-red colour in the tissues. They are blunt behind, but taper in front, and have two black hooks in the front end. The maggots change into pupae in the stem, and the flies emerge in May. They are of a glossy black colour, with a coat of golden-grey hairs; the head is chestnut-brown, with a black apex; the two wings are clear, with yellow veins; and the legs are straw-coloured, with dusky feet. The spread of wings is a little over 1/3in., the length of head and body hardly 1/4in.
Remedy. The only useful remedy seems to be the burning of all plants showing signs of disease, to prevent the injury from spreading.