AN INSECT DESTRUCTIVE TO TURNIPS. 69 
the work of destruction by feeding voraciously on the soft parts of the leaves of the 
turnip, leaving the fibres untouched : after a few days they cast their black skins, and 
then assume one of a more slaty or grey appearance ; they still continue, however, to 
feed on the leaves, passing from one to another. The destruction is complete, a whole 
field in a very short time presenting only an assemblage of skeletonised leaves, and this 
too even when the turnip itself has gained a considerable size. The caterpillar having 
passed through this feeding stage of its existence buries itself in the ground; and an 
exudation from its skin enables it to form for itself out of the soil, by the agglutination 
of particles, a strong oval cocoon. Some of the earlier broods passed very rapidly into 
the perfect insect, and were found on examination to be full of ova. 
The insect thus bred proved to belong to the order Hymenoptera, the family Tenthre - 
dinide or Saw-flies', the genus Athalia of Dr. Leach, and the species Centifolie of 
Panzer, described by Mr. Stephens in the seventh volume of his ‘ Illustrations of British 
Entomology,’ page 42, species 2, as follows: ‘‘ Head and antenne black ; mouth yel- 
lowish ; thorax luteous, with a large triangular black patch on each side, extending to 
the metathorax ; abdomen pale luteous, with the base of the Ist segment black, and 
the tip of the ovipositor in the female ; legs pale luteous, with the extreme apex of the 
tibie and of each joint of the tarsi black ; wings pale testaceous at the base, colourless, 
and with nervures fuscous at the tip; costa and stigma fuscous or blackish.” ‘‘ Length 
of body three to four lines, breadth with wings extended seven to eight lines?.”’ 
The larva or caterpillar is from half an inch to five eighths of an inch in length, and 
about the thickness of a crow-quill, with the head and upper part almost black, a 
lighter grey line along the side, six short articulated legs, and eight pair of accessory 
membranous appendages. On opening one of the cocoons on the 16th of November, 
the larva was found to have undergone little or no change at that time ; the caterpillar 
was alive and soft, and the inside of the cocoon was perfectly smooth, and exhibited a 
shining silvery-coloured lining. 
The crops of turnips in the counties of Kent, Essex, Sussex, part of Buckingham- 
shire, Hampshire, and Wiltshire were considered a failure ; and so long did the various 
broods continue their attacks, that the produce of a second and even of a third sowing 
1 From the serrated instrument on the abdomen of the females. 
2 The Rey. W. Kirby, who has perused this paper previously to its publication, has favoured me with a 
reference to an observation which is closely connected with its subject. Fabricius, who regarded the Ath. Cen- 
tifolie (Tenthredo Centifolig, Panz.) as synonymous with his Hylotoma Spinarum, the Ath. Spinarum, Leach, 
remarks in his ‘Systema Piezatorum’ with reference to the latter, ‘‘ Larva tota nigra victitat in Brassica Rapa 
quam destruit.” If these species be, as Mr. Stephens considers them, really distinct, the habit of destructively 
feeding on the turnip would consequently seem to be common to both Ath. Centifolie and Ath. Spinarum ; 
each of which occurs in this country. They are, however, so nearly allied to each other that the only distinc- 
tion between them indicated by Mr. Stephens is the colour of the antenne: and as this character appears to 
be variable in different individuals, Mr. Kirby is not disposed to regard the distinctness of the species as 
being yet definitively determined. In the individual figured in illustration of the present communication, a 
male, the antenne are of a dull yellow underneath. 
