1918] Leaf Eating Crane- Fly 77 



The behavior of the full-grown larva (Figure 1), presents 

 much that is interesting. The larva is invariably found on the 

 upper surface of the leaf and in the spring is actively engaged 

 in feeding. On a fresh leaf the larva usually begins by skel- 

 etonising it, leaving the lower epiderm intact. Later, however, 

 large holes are eaten completely through the leaf. 



Reference has already been made to the extraordinary 

 movements of the first-stage larva. These are much more 

 accentuated in the full-grown animal. The organs used in 

 facilitating its travel, are chiefly the mandibles and the abdom- 

 inal pro-legs or pseiido podia, ^ which are merely ventral protru- 

 sions, of the body-cavity two on each of the last eight segments. 

 They are apparently distensile, and it would appear as if they were 

 capable of secreting some kind of fluid that assist the animals in 

 retaining its hold on a smooth surface, especially so if the surface 

 be inverted. On the three thoracic segments there are no definite 

 pseudopodia, but the function of these is served by the develop- 

 ment of a distinct, ventral fold which becomes apparent as the 

 animal contracts. Two pairs of small tubercles or papillae on 

 the ventral surface of each thoracic segment, are also employed 

 in locomotion. 



In moving forward, the last segment is elevated from the 

 leaf -surf ace. Simultaneously almost with this action, the 

 middle region of the body contracts and arches so that one pair 

 of pseudopodia after another is methodically raised from the 

 leaf in a postero-anterior direction. The last segment comes to 

 rest in a position about half-an-inch anterior to its original one. 

 A series of rhythmical, muscular contractions pass wave-like 

 along the body from segment to segment, pulling the two extremi- 

 ties towards each other with the result that the body assumes 

 the shape of an inverted U involving at first only the abdominal 

 region. The contractions pass along to the thorax and head 

 which also become arched, whilst the pseudopodia of the last 

 five body-segments are applied to the leaf-surface again. The 

 inverted U is then composed of that part of the body anterior 



*The author has preferred to apply the name pseudopodia to the unsegmented, 

 paired tubercles of the abdominal segments because of their locomotory function 

 as well as their acting as adhering agents. They are charged with body fluid and 

 tracheated. The mechanism which determines their close application to a surface 

 is apparently blood pressure, and this together with the aid of the viscid fluid 

 which they secrete, is capable of maintaining the weight of the larva by surface- 

 tension on an inverted glass-surface. 



