82 
TURNIP. 
Have they disappeared altogether ? They are not noticed in your 
last Eeport, and I do not remember that they have been in the former 
Keports.” 
The Turnip sawflies are of a bright orange-colour, with black 
heads, and four transparent wings much netted over with veins (as 
figured), and yellowish at the base. 
The first brood of flies a,ppears in the early summer from out of 
the cocoons which have lain during the previous winter a little below 
the surface of the ground. The females lay their eggs on Turnips, 
and “ all cultivated plants of the Cabbage tribe, and many of the wild 
Crucifers, as Charlock, Winter Cress, and Hedge Mustard.”* 
The eggs are laid in small slits in the leaf, which are cut by the 
saw-like'' egg-laying apparatus of the female, whence this family 
takes its common name of “ Sawflies.” One female is stated to lay as 
many as a hundred eggs. The eggs hatch in a few days, more or less 
according to the state of the weather being favourable or otherwise. 
The caterpillars are stated to be greenish white when first they come 
out of the egg; afterwards they are black, with a paler stripe on each 
side; and later on, when nearly full-grown, are slate-colour (with a 
pale stripe as before), and pale beneath. They have in all'two-and- 
twenty feet (that is to say, a pair attached to every segment, excepting 
to the head and to the fourth segment from it, which is footless. 
The sooty colour, which they have almost throughout their lives, is 
the reason of the common names by which they are known variously, 
as “Black Jacks,” “Blacks,” “Black Palmers,” “Niggers,” &c. 
The caterpillar feeds for about three weeks, and then goes down 
into the ground, where it forms a cocoon, in which it turns to the 
chrysalis condition.! From this the perfect insect comes out during 
the summer, after about three weeks, or in a shorter time, if the 
weather is hot. Later in the season these changes are not gone 
through so rapidly, and in observations of the winter cocoons the 
* ‘ Praktische Insekten kunde,’ von Dr. E. L. Taschenberg, pt. ii., p. 319. 
t The description given by the well-known entomologist, the late Mr. Edward 
Newman (in his ‘Letters of Kusticus’), of the method of formation of this,earth 
cocoon is of much serviceable interest, showing, amongst other points, the thorough 
protection afforded by the case to the living contents :—“ When the ‘ nigger ’ has 
reached his full size, a period depending on the temperature of the weather and the 
supply of food, but averaging at twenty days, he burrows in the earth, and there 
makes a little oval house, just big enough for his body, which has all at once 
become shorter and thicker; he then plasters the walls of this place with a sort of 
sticky varnish or glue, which he discharges at this time only: he keeps on 
discharging and spreading this glue till he is quite surrounded with a strong, tough, 
and hard cocoon, the particles of earth being mixed with the glue, and the whole 
forming an admirable and perfect defence against wet and the attacks of insects.” 
—‘ Letters of Kusticus,’ p. 103. 
