504 Mr. C. L. Withycombe's Notes on 



closing the mouth opening is gradually drawn out of sight, 

 within the mouth cleft, as the head capsule hardens. The 

 mandibles and maxillae at first lie parallel, but after 

 hardening they engage with one another to form the sucking 

 jaws. 



Now the larva grasps the eggshell and withdraws the 

 anal extremity. Larvae sometimes rest on the empty egg- 

 shell for one hour, but others have remained as long as thirty 

 hours before wandering away in search of food. 



The first instar differs from the second or third-instar 

 larva in many respects besides size. Two may be mentioned. 

 The empodium between the tarsal claws is better developed. 

 In first-instar Hemerobiids and Chrysopids it is trumpet- 

 shaped. In the second and third-instar Hemerobiid the 

 trumpet form is lost and the empodium is small, but in 

 Chrysopidae this trumpet shape persists. The empodium 

 is both an adhaesive and tactile organ. When at rest it is 

 often not applied to the surface. Should an aphid brush 

 this empodium, the larva at once responds, but often an 

 aphid may brush the body or even the eyes without the 

 slightest notice being taken. Chrysopid and Hemerobiid 

 larvae have very poor vision and detect food mainly by the 

 sense of touch, the tips of the maxillae being extremely 

 sensitive. 



Eeturning to the first-instar larva, the second noteworthy 

 point of difference is in the number of setae and their 

 form. In Chrysopids the setae of young larvae are usually 

 curled at their tips or hooked, and most larvae at first 

 carry some debris on these. Later, hooked hairs are only 

 found on those forms which habitually carry debris. From 

 a single lateral wart, in first-instar Chrysopids, there 

 generally proceed only two setae. In the later instars, of 

 course, there is a brush of setae. All first-instar larvae have 

 fewer body setae than in later life. 



There appear constantly to be only three larval instars, 

 I have found no more in any case. 



The body of the second and third-instar larva is more 

 or less fusiform, slightly flattened dorso-ventrally. The head 

 is flat, encased in chitin which shows few sutures, though 

 such sutures are less pigmented as a rule. With its base as 

 the anterior margin of the head, between the jaws, is a tri- 

 angular plate of chitin, of which the apex is approximately 

 in the middle of the dorsal surface of the head. This is the 

 fused frons, clypeus and labrum. The labrum is often very 



