^06 The Ohio Journal of Science [Vol. XVIII, No. 6, 



region. At their bases the head is constricted visibly and at 

 this constriction there are four triangular chitinous processes. 

 These lobes may represent the mouth parts alone and may also 

 be considered as the rudiments of the head. They are very 

 firmly embedded in the tissue and are often detached and 

 overlooked. Eleven distinct ganglia of large size comprise 

 the ventral nerve chain, the first two being the largest. Beneath 

 the second exuvium the cast tracheae and their branches can 

 be seen. Nine spiracles are present. 



Fourth instar. — The exact status of this stage is not yet 

 determined. It is indicated only by the characteristic mouth 

 parts, (Figs. 13 and 14), and the exuvium has riot been noticed 

 if indeed there is more than a molting of the head parts. It 

 is obvious that the change from the peculiar soft lobed mouth 

 parts of the third instar to the heavy chitinized mandibles of 

 the last instar is too abrupt and that there must be an inter- 

 mediate stage probably having been mostly suppressed with the 

 specialization of the group. The mandibles in this stage are 

 distinct curved processes with broad rounded and notched 

 tips, thinly chitinized. A simple truncate labrum is present. 

 Shortly after this stage has been reached the fifth instar mandi- 

 bles develop back in the head, the point of each projecting into 

 •the base of the fourth instar mandibles. This instar is not 

 represented by any of the three exuviae composing the larval 

 sac. 



Fifth instar. — Shortly before the appearance of the larva 

 from the larval sac the mouth parts of the last instar are com- 

 pletely developed, and larvae dissected out of sacs showing the 

 three larval exuviae present the same type of mouth parts as 

 the mature free-living larva, (Fig. 15). Though fully developed 

 late in the preceding stage the cutting mandibles do not function 

 until this instar. The mouth parts are represented by the 

 rounded labrum, the dark brown, curved, sharply pointed 

 mandibles, the maxillge, and labium. Just dorsal to, and at 

 the base of, the mandibles are the irregular pigmented eye 

 5pots. Nine spiracles are present, the first pair being of large 

 size and brown color and situated back of the head on the 

 second thoracic segment. All the other spiracles are indistinct. 

 The body still retains the U shape, though now the anal extrem- 

 ity reaches only as far as the first or second thoracic segments. 

 If the mature larva is hairy as in the case of Aphelopus species. 



