174 FIRST ANJTUAL REPORT OF THE STAT.E ENTOMOLOGIST. 



the bulb is consumeci, they desert the plant for another, and still others 

 in succession, as a dozen or more young onions would be needed to 

 furnish the requisite amount of food for maturing a half-dozen of the 

 larvge. 



The larva when full grown, shown at c, in the accompanying figure 

 and at d, in enlargement, is nearly one-third of an inch in length. It 

 is glossy, dull white, smooth, naked, of an elongate-conical form, with 

 its anterior end capable of being extended, while feeding, into an acute 

 '^ ^ A ^^^^EIII> point. At the extreme end, the two 



^ black hooks which form the cuttins: 



ocwi 



organs of the mouth show through the 



skin as a short black stripe. Near the 



^ ^ , . , r. ■ J head, the protecting breathing organs 



FiQ. 47.— Early stages of the Ouion- ..,ia ? i 



fly: «, eorgs, uaturai size, 6, enlarged ; c, are Visible. A stripe Seen along the 



d, the larva, natural size and enlarged ; •in e 'l \ ^ • ix. t i. _ 



e,f, the paparium natural size and enl middle of its back IS the alimentary 

 larged. (After Fitch.) vessel with its Contained substance. The 



hinder end of the body is obliquely truncated, and on its flat surface 

 are two small elevated brown points (the spiracles or breathing tubes 

 of this extremity of the body), and on the margin are eight small pro- 

 jections, like teeth, of which the lower two are the larger. Slightly in ad- 

 vance of these latter are two small processes which appear to be of 

 service to the larva in its travels. Some prominent folds — one on the 

 under side of each segment — are also aids in locomotion. 



Pupation. 

 In about two weeks in summer, the larva has attained its growth, 

 and is in readiness for its pupation. In a number of recorded instances 

 it has assumed this stage within .the onion, but it usually with- 

 draws itself into the surrounding ground. It has soon contracted in 

 length and become of an oval form, moderately pointed at its anterior 

 end, and somewhat flattened at the other, where projections resem- 

 bling those of the larva may be seen. The skin has hardened and has 

 chane:ed to a chestnut-brown color, and in this condition resembles 

 some of the pupal forms. It is not the pupa, however, but only its 

 envelope or case protecting the true pupa, which, upon breaking open 

 the outer covering a few days after its formation, would be found as a 

 soft and white body showing the jointed abdomen, with the wings and 

 legs of the future fly appressed to its surface. This case, which shelters 

 the inclosed pupa like the cocoon of a moth, is known as a puparium.* 

 It is shown in Fig. 47, at e in its natural size, and at/ enlarged. 



*It is described by Westwood as " of a chestnut color, having its posterior end blackish 

 with the extremity red, and two large black spots observed in the larva ; the oral tentacula 

 are also observable at the other end, they being somewhat exserted." {Mag. Nat. Hist., 

 vii, p. 428.) 



