THK YOUNG NATURA.LIST. 



55 



Family XII.-Lithocolletid.«, Stn. The 

 cts comprising this family are all very 

 small, but ver\' beautiful. They are double 

 brooded, appearing in May and August. 

 The lar\'ae have only fourteen legs and mine 

 the leaves of various trees, sometimes on 

 the upper side of the leaf, but generally on 

 the underside, changing to pupae in the 

 mine, and pass the %sinter in that state. In 

 this state they are easily collected in fallen 

 leaves. i 



Family XIII. — Lyonetid.e. Larvae mine I 

 the leaves of plants, or under the bark. 

 Some mine when young, afterwards feeding 

 externally. 



Family XIV. — Nepticulid.€, Stn. Some 

 of the species of this family are among the 

 smallest known Lepidopterous insects. 

 Many are adorned with gold or silver. The 

 larvae have no true legs. They make long 

 serpentine mines in the leaves of plants. 



NOTES ON A DIPTEROUS 

 PARASITE OF PLUSIA 

 V-AUREUM. 



By C. H. Walker, Liverpool. 



About the beginning of May last, I 

 received from Mr. Miller, of Gateshead-on- 

 Tyne, a nearly full-fed lar\-a of this moth, 

 which he informed me was infested with a 

 dipteron. If I remember rightly, he stated 

 that at least 60 per ccnt. of the larva he 

 ': were attacked, a circumstance that 

 - r.siderably interfered with the breeding 

 of this beautiful insect. The larva, when it 

 .:hed me was of a rich apple-green colour, 

 n an indistinct medio-dorsal vessel, 

 succeeded on each side by three delicate 

 ite lateral lines. In walking, it bent its 

 iy like a Geometer. On a casual glance 

 at the larva, it appeared to be of a totally 

 different species, due to a dorsal row of nine 

 black, circular spots, whose positions were 

 as follows :— Four black spots situated res- 

 pectively on the fourth, fifth, sixth, and 



seventh segments, on the immediate left of 

 the medio-dorsal vessel ; two others on the 

 eighth segment, one in the centre, and the 

 other below it, on the left; and finally, one spot 

 on the ninth, tenth, and eleventh segments 

 respectively, the first and last being on the 

 right, and the second on the left of the same 

 vessel. Under the lens, each spot appeared 

 as a puncture, the surrounding skin being 

 slightly discoloured. It fed voraciously on 

 Urtka dioica, until the 17th May, when it 

 perceptably changed. It began to swell 

 out, lost its vivid green colour, which was 

 replaced by a pale greenish white tint, while 

 the skin became singularly transparent. It 

 then refused all nourishment, and selected 

 a comer of the box, where on May i8th, it 

 spun a slight web, and resigned itself to its 

 inevitable fate. Up to the 20th instant, it 

 darkened in colour, becoming a dirty grey, 

 and on the 21st it gave the first indications 

 of the actual presence of the parasite. It 

 began to contract at the interstices of the 

 of the segments, each segment being con- 

 siderably distended, and the whole cater- 

 pillar presented the appearance of being 

 tied by thread in eight different places. It 

 seems strange that the parent fly should 

 have deposited two eggs in or on one seg- 

 ment, and that only eight flies should make 

 their appearance, there being certainly nine 

 cocoons, one remaining unhatched, which 

 upon being opened disclosed the dead fly. 

 This is the only example that has ever come 

 under my notice, of a number of larvae of a 

 Dipteron living gregariously in the body of 

 their victim, changing to pupae within the 

 empty skin of the same, and using the latter 

 as a protective cocoon. The case is exactly 

 the reverse in a small dipterous parasite of 

 Bombyx quercus. The grubs, to the number 

 of forty, or thereabouts, live within the 

 caterpillar, but on the approach of their final 

 stage, they leave the quercus a lifeless wreck, 

 and become pupae unenclosed in any 

 cocoon. 



