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Psyche 3:99-103, 1880.

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PSYCHE.
THE TROPHI AND THEIR CHITINOUS SUPPORTS IN ORACILARIA. BY GEORGE DIMMOCK, CAMBRIDGE, MASS.
The papers upon Lithocolletis by Mr. V.
T. Chambers, which have appeared from
time to time in PSYCHE,^ supplemented by the notes and figures on the same subject contained in his address as retiring presi- dent of the Cincinnati Society of Natural History,2 inspired me with the desire to study further the mouth-parts of the larvae of Tineina, especially in their earlier
stages. The abundance of Gracilaria
ayringella in the leaves of the lilac (Sy- ringa vulqaris), about Leipzig this sum- mer, gave me plenty of material, and the opportunity of studying the larvae under the direction of Professor Leuckart was not lost.
Altho the larvae were so numerous in
some of the gardens about Leipzig that
scarcely a leaf of the lilac escaped their depredations, I attempted to learn but little of their mode of life. During their early stages, when they have the flattened larval form, they mine in the upper side of the leaf. They then have the form of head
and mouth-parts represented in fig. 2, and their legs are mere rudiments. A little
PSYCHE, Nov.-Dec. 1877 [April 18781, v. 2, p. 81-87 ; May-Aug. [Nov.] 1878, v. 2, p. 137-153; April 1879, v. 2, p. 227.
later they assume the form of head and
mouth-parts shown in fig. 3, and begin to eat away all the parenchyma of the leaf, leaving only the upper and lower epider- mis; still later they leave the mines and roll the ends of the leaves, feeding within the rolls. Upon changing the form of
mouth-parts from that represented in figure 2 to that represented in fig. 4, true legs are developed, the secretion of silk is begun, and the larvae become more cylindrical.
A striking resemblance to the changes
which Mr. Chambers has observed in the
cylindrical larvae of Lithocolletis is ob- served in the above-mentioned changes of the larvae of Gracilariu. Often as many
as ten or fifteen larvae are found in a single blotch on the leaf. I succeeded in rearing the larvae easily by simply transferring leaves containing them to a box, in which I packed many leaves closely together.
The leaves, thus packed, retained moisture and the larvae deserted the mines to wan- der about between the leaves, where they fed until ready for pupation. I am in-
debted to Professor Zeiler, for the determ- 2 Journ. Cincinnati Soc. Nat. Hist., July 1879, also Separate, 22 p. [PSYCHE, Rec., no. 1805.1



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ination of the species of &&laria which tims of thin ring there passes forward, on I have bad under observation. each side, a support (fig. 2, a), which turns In order to make the structure of the
suddenly inward and ventrally behind the trophi and the arrangement of their chit- antenna (fig. 2, p), and helps to form the inous supports more clear, I ham prepared socket of the joint, of the mandible. About fig 2-47 to accompany the following de- half way between tire lateral supports (fig. scription.
2, a) and the middle of the ventral portion- The head of the early form (fig. 2) is of the head, on each side, there passes for- much flattened.
It has, upon its dorsal ward from the ring which surrounds the surfac% two stout chitinous supporh which posterior portion of the head another sup- Paas anteriorly to a point above the labrum, port (fig. 2, b) , which also helps to form where they nearly meet, then turning hfc. the socket of the maadibu1m joint. From
the points where the last-mentioned sup- ports join the posterior ring, supports (fig, 2, d) pass anteriorly and obliquely toward the dorsal side of the head, joining the dor- sal supports about midway between e and
the labrum.
The labrum of the early form (fig. 2, o) is supported beneath the d:verpt mterior extremities of the dorsal chitinous supports of the head in such a manner as to be ca- pable, not only of some protrusion and re- traction, Unit also of a slight, lateral motion. The lab-rum is bilobed, each lobe bearing FIG. 2. - Ventral view of the head of Graci- larut sp+geJ/a in its early *ta.e~ : 0, la- five incurved Vine87 and b a very delicate tourn ; R, mandible ; r, maxilla; p, antema; a, grooving (fig, 3, 0).
!i, d, e, ,f, g, li, i, m, chi tinom supports explained in the text; q, clepres~ion between the basal sup- The miwidibie8 of the
form (fig*
port of the maxilla and the ventral siirfncu of the and 3, w) are strongly chitinized, They lead.
are of a generally triangular form, strongly erally and ventrally, at nearly right angles rounded on the outer ride and toothed on to their previous direction, they join with the inner side. Two prominent apical other chitinous supports to form the sockets teeth are followed by a number of smaller of the mandibdarjoints. Posteriorly these ones. On the under-side of each mandi- two dorsal supports (the anterior portions ble, near the middle of the proximal end, of which are not seen in fig, 2) approxi- is a rounded protuberance, which fits into mate slightly and are connected by a trane a socket formed by the union of the aup- verm support (fig. 2, e) ; rapidly diverging ports a and b with the laterally divergent again they join the ring which
passes anterior portions of the dorsal supports of around the posterior portion of the head the head, thus forming the mandibular
(fig. 2, f, m, g). From the lateral For- joint. The pinm&rm extensor muscles of



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the mandibles have their insertion on. the exterior proximal angle of each mandible and their origin on the chitin supports a and b. The broadly pimuform flexor mua-
des of the mandible^ have their insertion on the interior proximal angle of each
mandible, and their origin on the chidnoua supports a and mi and on those which pass anteriorly and posteriorly from the support e ; they thus lie dorsally and the extensors ventrally. The mandible8 are directed ex- actly anteriorly, in the axis of the body ; and. not ventrally.
The maxillae (fig. 2 and 3, r) and the
labium (fig. 3, w) in the early form are attached to a common protmsile basis, the limits of which are partly indicated at q (fig. 2). The maxillae are very rudiment- ary, but that they are maxillae is shown by their being deft, for if they were labial palpi they would not be cleft, but would probably be jointed. Further, as nearly aa could be determined from a number of lar- vae found in the act of molting, at the time when they pas9 from the earlier to the later form, the maxillae of the later form were drawn from the skins of these cleft appen- dflges. la still farther support of the view that the month-partg are maxillae is their position, which is with their apical extrem- itiea slightly above the level of the labium, as can easily be seen by careful focusing with a high-power objective. The DUX-
ihe of the early form, then, are only lat- eral, outwardly-curved, processes, each aide of, and attached to the same support as the labium.
The labium of the early form (fig. 3, v) is bilobed, with a few delicate grooves and thiekeninga, and is covered distally with a rasp of fine ~pinea. It can be protruded, together with the maxillae, beyond the ex- tremities of the mandibles, and has a slight lateral motion. No traces of a spinneret are visible in the early form of larvae. The support common to the maxillae
and labium consists of two chitinous rods (fig. 2, i) passing posteriorly, diverging slightly, and then suddenly curving in-
ward. The support is retracted by a mu-
cle between the posterior ends of thew
chithow rods (fig. 2, 7i) and a part (fig. 2, g) of the ring at the posterior portion of the head. I was unable to discover
Fio. 3. -Comparison of the separated mouth- parts of the early and later larval stages of &a- m~ syiage7lu : v, v', labintn of each form ; t, labial palpus of later form.
any opposing muscle, and I think the labic- maxillary support is protruded by the ac- tion of the fluids of the head.
After the molting by 'which the larva
enters upon its later or more cylindrical stages, the head becornea broader and
thicker in proportion to its length, a few haira appear on its anterior portions, the mouth-parts are directed a little ventrally from the axis of the body (fig. 41, and the condition of the trophi and their supports is as follows : -
The chitinous supports of the parts of
the head are somewhat modified from what



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they were in the early form of larva, altho The maxillae in the later form (fig. 4,
they are only a further elaboration of the r; fig. 3, r') have undergone considerable me plan.
The support e (fig. 2) has change in their appearance from that in the ecome so- rednced that the dorsal supports early form. They are now of the form
appear simply to cross one another (fig. 4, common to lepidopterons larvae - an out- e) .
The supports which pass anteriorly ward jointed portion, the maxillary pftlpm, from e have united at their ends to form a and a double inner jointed portion, the (not shown in the figure). The sup- maxilla proper. f (fig...2), which was slender in the
The labium (fig. 3, v') has, in the later y form, has entirely disappeared.
The form, developed a pair of jointed labial oxta a and m remain essentially the
palpi and a tubular spinneret. The proxi- they were in the early form, but b,
mal portion ie hairy. Not only the spin- t first united almost directly with d, neret, but also the labium itself, can be has become separated from it, to allow of the interposition of a support c, which
passes forward and unites, at I, with a
branch (k) from 6, the whole portion at t serving aa attachment for a muscle to
extend the labium and maxillae. The
chitmona supports of the labium and
maxillae have changed, aa will be seen
later.
The labrum (fig. 4, o ; fig. 3, 0') has
nearly the same outline as in the early form. The anterior portion, especially in the very last larval stage, is beset with hairs. It and elightly movable laterally, aa is the early fom.
turned under, 80 that the labial palpi are The mandibles (fig. 4, n; fig. 3, n')
directed posteriorly. The position shown have characters similar to those which in fig. 3 is with extended labium ; in fig. they had in 'the early form.
The small 4, with labium folded back,
teeth are, however, absent, and, in their The supports which bore the labium and
place, a ridge extends along the under aide maxillae in the early stages (fig. 2, t) are of the mandible from the large apical teeth greatly modified in the later stages. The to the base.
The origin and insertion of support i (fig. 4) divides posteriorly into the extensor and flexor muscles are on two parts, between the ends of which ex- places corresponding to their origin and tends a support, h (fig. 4). The slightly insertion in the early form.
developed line of demarcation between the'



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PS YCEE.
maxilla and the under surface of the head walk, from which they feed, and, in many (fig. 2, a) has become a clearly deffiaed eases, on which they @pin their silk. line, and the whole supporting framework This successive development of organs
of the labium and maxillae approaches a coordinate with their fimctiona is well rectangular form, limited posteriorly by exemplified in the larvae of GracHarW., of chitinous supports (fig. 4, h, h') .
Muscles LithOCo!Zet&, of Phyllow-tStW ' and possibly extend from them chitinous suppork, h, A', of other Tineiiia, in which the early form anteriorly to the chitinous rod. I and nos- of the larva is so different from its later teriorly tothe rod a. The action of these form. In ffrwila?+a, @g&, BO long ~~iselesprotrndea orretracts theframework as the larvae feed only in a plane surface, of the labium and maxillae, but, while the and do not ~ph, no great difference ia visi- maxillae are simply pushed forward by ble between the mouth-parts above the this action, the labium is unfolded, or Qn- mandibles and those below them. Both
rolled, BO as to assume the position shown labnim and labium exercise their simplest in fig. 8, v'.
functions of pushing the food between, and If the form of the trophi in GraciIa&z keeping it subject to the action of the man- U a , in its early larval stagea, be dibles, and, perhaps, of sawing it out of compared with the form in the later larval the parenchyma by a lateral motion. But
stages, the modification of each part will contemporaneous with the appearance of be seen to increase in amount as the dis- the later forn't of larval trophi, - the la- tance from the anterior part of tile head bium capable of trdng under, and the increases, that i~, the mandibles change better developed maxillae - the larva, now more than the labrum, the maxillae more having its mandibles directed afightly Ten- than the mandibles, and the labium moat trally, acquires the power of eating verti- of all.
By comparing, on fig. 3, the month- cally to the surface of the leaf, and of parts of the early and later forms, the
spinning threads in all directions. At the changes of die labram are aeen to be same time its feet are developed, later it moat17 in mkhg~, and in tho numbex of eab out frm ib mine, and bemmsg frea hairs or spines ; the changes of the man- An externally well-differentiated dorsal and dible have been, to a slight extent, mod%- yentrd ~urface seems to have been acquired cations of form ; the maxillae, while they from the time when the larva ceased to be existed before, are greatly modified in the pressed dorsally and ventrally between the later form; the labinm most. of all seems upper and lower epidermis of its mine. to have added to its structure and fimctions. I have not had the opportunity to oom- This increase of complexity of the mouth- pare, by microscopic work, the larva of parts toward the labium, which becomes QrwIlarW qd~gello, with other larvae of more and more striking at each gticceasim Tiaeioa ; therefore the above observations stage in many insects, is probably coordh- may be regarded aa quite incomplete. ate with the relations which them parts Leipzig, I5 Aug. 1880. . have to the surfma on which the larvae ah~taut, May [XQJ 1880, T. 3, p. 67.




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