256 



THE AMERICAN ENTOMOLOGIST. 



The larvae of Lithocolletis are divided 

 into three groups, known as the flat, the 

 ornatella or intermediate, and the cylindri- 

 cal groups. In the flat group, the larvae in 

 their first five stages are flat, have membra- 

 neous, retractile thoracic, ventral and anal 

 legs, and trophi of the "first" form. At their 

 5th molt they become vertically thickened 

 and more cylindrical, and assume trophi of 

 the " second " form, with, however, the 

 mandibles small and functionless ; their 7th 

 stage is like the 6th, they never acquire ar- 

 ticulated legs, and they pupate in the mine. 

 In L. ornatella the first five stages resemble 

 the first five of the flat group, but the larva 

 is not so much flattened ; but at the 5th 

 molt the larva becomes approximately 

 cylindrical, has well-developed articulated 

 thoracic legs, and trophi of the 2d form, 

 with the mandibles large and strong. 

 Neither of these groups of larvae eat any- 

 thing in the 6th and 7th stages, and onia- 

 tella (the only known representative of its 

 group), leaves the mine to pupate. The 

 larvae of the cylindrical group, in their first 

 three stages, resemble those of the two pre- 

 ceding groups, being flat, with trophi of 

 the first form and membraneous legs, but 

 they are more elongate and slender. But 

 at the 3d (instead of 5th) molt, they ac- 

 quire well-developed articulated thoracic 

 legs, with trophi of the second form, and 

 large, strong mandibles, and a cylindrical 

 form ; they, like the flat group, pupate in 

 the mine. The larva of Leucanthiza aviphi- 

 caj-pecefoliella (Clem.), the only representa- 

 tive of the genus, in form, structure, his- 

 tory and habits resembles very closely 

 Lithocolletis ornatella. The larvae of Gra- 

 cilaria, Ornix and Coriscium, in their first 

 stage, resembles those of the flat group of 

 Lithocolletis, but at their first molt they ac- 

 quire a cylindrical form, well-developed 

 thoracic legs, and well-developed trophi of 

 the second form, and then resemble the 

 larvae of the cylindrical group of Lithocol- 

 letis. They have only five larval stages, 

 and their habits as to pupation are various. 

 Some never leave their mines except to pu- 

 pate. Some leave one mine and make 

 another after their second rnolt ; and some. 



after that molt, feed externally. All the 

 larva above mentioned have three pairs of 

 thoracic, three of ventral, and one of anal 

 legs. The larvae of Phyllocnistis have no 

 thoracic legs, but have eight pairs of mem- 

 braneous retractile abdominal legs, and an 

 anal pair. They are flat, with trophi of 

 the first form, except in their last stage, 

 when they are oblong-conical, and have 

 greatly aborted trophi of the second form. 

 They pupate in the mine, which they never 

 leave until the imago is disclosed. 



These facts have been elsewhere previ- 

 ously stated by me, but for the better un- 

 derstanding of this paper it is deemed best 

 to repeat them here. 



Fig. 124 represents the trophi of the larva 

 of Lithocolletis ornatella Cham., and Fig. 125 

 those of L. guttifinitella Clem, in their 7th 

 and 6th larval stages; but, as will presently 

 be shown, they are very different from the 

 trophi of the same species in the five pre- 

 ceding larval stages; as, indeed, will be 

 evident at a glance, by comparing Figs. 124 

 and 125 with Fig. 126, which represents tro- 

 phi of larvae of either species in their first 

 five stages. In Fig. 124 and 125 "di" is the 

 labium with spinneret, and with the i)alpi 

 on each side; "^," maxillae with palpi; "^." 

 mandibles; 'V," antennae; "^," labrum and 

 "/," eyes. The only notable difference in 

 these figures is that the mandibles are much 

 larger in Fig. 154 than in Fig. 125. I form- 

 erly thought that this difference might be 

 owing to the different habits of the larvae. 

 The larvae of L. giittififiitella, and all of the 

 allied species, forming what is called the 

 flat group, in allusion to their form, do not 

 eat after their fifth molt; and never leave 

 the mine; and, except that they spin their 

 cocoons in the 7th stage, their 6th and 7th 

 stages are as completely quiescent or rest- 

 ing stages as is the pupa state. Neither 

 does the larva of L. ornatella, (which, of 

 itself, forms the second group) eat in the 

 6th and 7th stages; but in its 7th stage it 

 cuts a lunate slit in the cuticle of the leaf; 

 leaves its mine, and crawls away to pupate 

 elsewhere. 



The larva of L. ornatella is also, in 

 its 6th and 7 th stages, supplied with well- 



