16 



CELERY. 



part was, in some instances, completely killed, this involving gradual 

 death of the roots and of the whole plants. The maggot galleries often 

 extended some way up inside the stalks of the leaves. This exactly 

 corresponds with the description given by Prof. Westwood of " the larva 

 burrowing into the solid stem and fleshy stalks, working its way up the 

 latter." 



On the 3rd of August, I found several maggots had left the Celery, 

 and were moving about in the dry earth, on or in which the Celery 

 was laid. These were about a quarter of an inch in length, or rather 

 more when extended, yellowish white, and very shiny, and somewhat 

 transparent ; the shape cylindrical, narrowed at the head extremity, 

 which is pointed when in movement, and obliquely rounded at the tail, 

 which is furnished with two black spiracles ; these are noticeable 

 with an ordinary low-power hand-magnifier. 



With an inch object-glass the spiracles appeared to be joined at 

 the base by a black substance, and the tracheae might be clearly 

 observed passing on from the spiracles into the larva. At the anterior 

 extremity (i. e., towards the head end of the maggot) the tracheaB were 

 furnished with external and branched spiracles, and, so far as the 

 movements of the maggots would allow of counting these branches, 

 they were about six in number. It was only occasionally that I could 

 gain a sight of the expansion of the branches in which the spiracles 

 terminated, so that for the most part these appeared simply exserted 

 without division ; but with a quarter-inch glass, and the larva at rest, 

 I was able to make out clearly that one spiracle had six branches, 

 besides what appeared to be the broken remains of another. The larvas 

 frequently curled themselves into a circle, head and tail together. 



I am not aware of any description having previously been given of 

 this larva, excepting that published by Prof. Westwood on his first 

 observation of the attack in 1843 (see previous reference), of which I 

 therefore append the main points, to show the similarity of the infes- 

 tation. 



" The larvas are glossy white, cylindrical, grubs, having the anterior 

 part of the body pointed, and the hind part obtusely rounded and 

 marked by two black points, from whence proceed two delicate air- 

 vessels, appearing like threads of gold beneath the transparent skin, 

 and which run along the whole length of the body, as far as the segment 

 immediately behind the head, where they form two minute exserted 

 appendages." . . . " The mouth consists of a black horny apparatus, 

 capable, as well as the head itself, of being withdrawn into the subse- 

 quent segment, as far as the two exserted lobes of the air-vessels above 

 mentioned." — (J. 0. W.) 



Amongst the specimens sent to myself from Epworth, a second 

 kind of dipterous maggot was present, but, as far as I could judge, only 



