Use Of The Mouth Parts Of Orthoptera During Feeding (1960)

for years one or another species of grasshopper which are insects of the order orthop have been chosen as types to illustrate the mandibulate or biting mouth parts of insects it is somewhat surprising then when one finds that little is known about the way in which their mouth parts are used during feeding which is our concern here first let us describe the more superficial aspects of feeding in the grasshopper Aria sufuria it like other grasshoppers feeds by means of a technique here called margin feeding in margin feeding a grasshopper mounts a leaf usually straddling its Edge the animal first swings its head dorsad or upward carrying its mouth Parts far forward it then moves its head in a ventral CAD or backward and downward swave as it cuts food from the edge of the leaf by this means a small excavation is made in the leaf margin this is deepened and elongated during successive SVS each cutting deeper into the wound when the injury has been enlarged to a point where it can no longer be deepened easily the insect moves its body forward and attacks an adjacent portion of the leaf let us consider in detail the way in which the Grasshoppers mouth parts are used in the feeding process here is a drawing of romalia microptera with the animals mouth Parts in feeding position the parts in which we are interested are the labrum or upper lip the mandibles or Jaws the max or second pair of Jaws and the labium or lower lip now let us examine each of these parts separately here we see the laum it is a flap-like extension of the head capsule and in a strict morphologic sense not a true mouth part it bears at its apex a laboral imgination the mandible or jaw is seen next it Bears a molar area the dents or teeth of which are used for chewing and an incer area the dents of which are used for cutting food contrary to most illustrations seen in textbooks the mandibles are clearly asymmetrical that is unequal in form if this were not so they would not be able to olude or intermesh to cut and grind food here is the maxela the most conspicuous parts of which are the cardo or basil segment the stipes the lysia or toothed portion the Galia or lip-like portion and the palpus a ferike structure immediately beneath the maxilla is the labium which morphologically Speaking is composed of two fused maxel its more conspicuous parts are the palpy the mentum and the ligula the latter includes two very large parag glossy and two very small glossy the Groove partly subdividing the labium may be termed the laal groove now that we have examined the structure of grasshopper mouth Parts let us see how these parts are used individually and together in feeding this is A View From Below showing the grasshopper ramalia microptera feeding on a leaf which can be seen down the middle of the ill rtion here is an individual of the grasshopper moplus differentialis differentialis engaged in feeding notice that as the insects mandibles come together a small portion of food is removed by the incer dents this food is slowly masticated by the molar dents and then swallowed in this species each period of incision is followed by one of mastication the animal's laum is pushed toward its Base by the incoming food which is aligned by the laboral imagination the action of the maxel is more difficult to observe but if one watches closely a glimpse of the lini may be had thein operate out of phase with the mandibles that is when the mandibles come together thein separate and when the mandibles separate the lini come together to convey cut food into the pre-oral cavity where it is masticated by the molar dents and then swallowed the gal do not actually handle food but merely act as lateral lips the action of the palpy is clearly shown they drum tap and press against the food so that it is kept aligned at all times the food does not necessarily align with the medial groove of the soft laum now in review in the margin feeding of grasshoppers the insect attacks a leaf by a series of ventrad or backward and downward SVS with its mouth Parts the leaf margin invariably aligns with the animals laboral imagination the incer dents of the mandibles cut the food and the molar dents masticate it there is usually a distinct pause for mastication following each period of incision thein which operate in opposite phase to the mandibles Force the cut food into the pre-oral cavity where it is masticated and swallowed the g e do not handle food but function only as lateral lips the food margin may or may not align with the insects laal Gro this then is a view of a little known phenomenon the use of the mouth parts of a grasshopper during feeding [Music]