74 



THE MONTHLY BULLETIN. 



develop flowers, but are lacking in sufficient vitality to reproduce more 

 bulbs. The infestation is often very difficult to detect, especially in 

 cases where this period has been of short duration. The best method of 

 ascertaining the presence of a larva, or a bulb that has been hollowed 

 out by the feeding maggot, is recommended by Mr. R. Stewart Mac- 

 DougalP as follows: "It is often difficult to sayVithout opening a bulb 

 that a Merodon grub is present within, but in typical cases, when the 

 grub has been at work for a considerable time, the infestation can be 

 recognized by the bulb 'giving' on being squeezed between finger and 

 thumb. ' ' 



Fig. 18. — Larva of the Narcissus bulb fly and infested lily bulb showing the char- 

 acteristic feeding habits of the insect. (Original.) 



Larvae. The larvae (Fig. 18) are very conspicuous, light grey grub- 

 like maggots, measuring from one half to three fourths of an inch in 

 length and about 2| times as long as broad. The segmental rings are 

 very distinct and deeply indented ; the body is decidedly arched on the 

 dorsal surface and flattened on the under side. The head can not be 

 differentiated from the rest of the body. At this end are two mouth 

 hooks and a pair of spiral openings or breathing tubes. Both hooks 

 and tubes are composed of rigid black chitin. On the posterior end 

 near the center is a small black projection, flattened at the extremity 

 and much resembling the snout of a pig in outline ; two openings may be 

 noticed by close observation. These are the posterior spiracle apertures. 



'Narcissus Flies, R. S. MacDougall, Journal of the Board of Agriculture, October, 

 1913. 



