342 TRANSACTIONS OF THE 



5. Remarks on the Turoiip-Fly. By Henry Le Keux, Esq. 



On examining the leaf of a turnip against the hght with 

 a magnifying glass, I perceived a larva between the upper and 

 under surfaces, which eventually proved to be that of the 

 Altica nemorum, or little beetle, commonly known by the 

 name of the Turnip-fly. On removing the earth from the root 

 of the plant from which this leaf was taken, I found both 

 larvw and pupw. I have previously attempted to breed the 

 Altica, by keeping a number in a small box covered with 

 gauze wire, and dropping in fresh pieces of turnip leaf daily ; 

 in this manner I kept them alive from July till February : but 

 it appears it is essential that the leaf should be in a growing 

 state, otherwise the t^^^ shrivels up and dries with the leaf. 

 Still being unacquainted with the origin of the/a?T«, I captured 

 ten pairs, and enclosed them in a glass tube, with a turnip leaf, 

 and water to keep it fresh ; by this means I could examine 

 them with a glass without disturbing them. Next day I found 

 five smooth, oval-shaped eggs attached to the under side of the 

 leaf, and very nearly of the same colour. The leaf was re- 

 moved and placed in water, and a fresh one supplied, which, 

 on the following day, had three eggs on it. I found great 

 difficulty in preserving the leaves sufficiently long for the eggs 

 to hatch ; but I provided against this by placing fresh leaves 

 by the side of the old ones. The eggs hatched in ten days, 

 and the larva immediately began to eat its way into the leaf, 

 and form a burrow by feeding between the upper and lower 

 surface; this burrow is scarcely obvious until it has become dry. 

 The larva is full fed, and goes into the earth at the end of 

 sixteen days, to the depth of an inch and a half, always under 

 the shelter of the turnip leaves. I believe the time passed in 

 the chrysalis state to be about a fortnight, although I have 

 been unable to ascertain this with accuracy. The perfect 

 insect appears to fly only in warm sunshine, or when the ther- 

 mometer stands as high as 70° in the shade. They pair in 

 May, June, July, and August. In the winter they live in 

 crevices of timber, bark of trees, and in loose dry banks; from 

 these hiding-places they emerge, even in winter, on the occur- 

 rence of a warm day. In cold weather they are torpid and 

 inactive. All remedies at present suggested for destroying or 

 driving away the fly are ineffectual. If Swede turnips are 



