15 

 CHIRONOMID PARASITE AND ITS EFFECTS. 



JOHN H. ASHWORTH. 



MiALL and Hammond, in their Monograph on the Harlequin 

 JFly, warn students against the irregularities and troubles 

 they will experience from the presence of parasites in the 

 sections under microscopic examination, particularly mention- 

 ing Mermis as infesting Chironomus larvae. 



In August last an example was found of Chironomus 

 plumosus showing female antennae, but with anal appendages 

 like those of the male. Three or four weeks later about half- 

 a-dozen similar specimens were seen on one evening. Three 

 of these were secured, and when examining them through the 

 lens a few minutes later, a worm was seen to be protruding 

 from the abdomen of one of them. The worm continued to 

 emerge and wrap itself in a coil, the halteres of the fly mean- 

 while developing a blood-red tinge. During the evening the 

 second specimen, the mid -femora and tibia of which had mean- 

 while acquired a reddish colour, also produced a green worm ; 

 the third was therefore placed in a separate tube to await 

 results. Nothing further showed next day, but on the morning 

 following, the fly was found to be dead, part of the genitalia 

 being bright red, while a dark, smooth, green worm about 

 an inch long also occupied the tube — the difficulty being to 

 understand how such a large parasite could have been stowed 

 in such a small host — less than a half inch in full length. 

 On examining the August specimen it was seen also to be 

 bearing a partially-emerged green worm, so that there would 

 appear to be some connexion between the dual sexuality 

 displayed by these Diptera and their being infested by this 

 Annelid parasite. 



Considering the zeal displayed by some systematists in 

 the past, our fauna might easily have been enriched by two 

 or three new species, if not another genus, our present classi- 

 fication including numerous cases of species differing by little 

 more than the colour of the halteres or a joint of the legs, 

 whilst under a lens and low power of the microscope the third 

 specimen (which seemed a true hermaphrodite) showed another 

 joint to the antenna, as if it were a male near Smittia Holmgr., 

 Telematogeton Sh., or Chasmatonotus H.Lw. (Kieffer in 

 Genera Insectorum.') Under a higher power, however, the 

 number of joints might be put down as anything from seven to 

 ten, according to the ideas of the observer, to the lasting con- 

 fusion of succeeding workers having a difterent idea as to what 

 constitutes a joint. 



Later in September, and afterwards in October, numbers 

 of females were taken, some of which proved to be infested 



1921 Jan. 1 



