THE CHIRONOMID.E. 171 



in the amber, we find many records in the Tertiary rocks of Aix, 

 Rott, Radoboj, Utah, and Wyoming. They are abundant also in 

 the Florissant beds, but, as in all other insects there, they are badly 

 preserved. There are also records of this family from the Tertiaries 

 of British Columbia. We thus see that during the Tertiary period 

 the distribution of this family was, as it is now, very wide. 



Geographical distribution. — The present distribution in space of at 

 least three of the genera in the Chironomid?e is very wide, the genera 

 Chironomus, Tanypus, and Ceratopogon being abundantly represented 

 in Europe, up into the cold Northern regions and in the warmest 

 parts alike in abundance. In America they are all abundant ; 

 whereas such genera as Corynoneiira, Diainesa, etc., are scantily 

 represented. In Africa large swarms of Chironomidre are found over 

 and around the lakes and lagoons, and in India and Australia they 

 are also largely represented, especially the three genera first 

 mentioned. 



Larz'ce of Chiro?w>ni. 



The larvae in this family have been very thoroughly investigated in 

 several types, on account of their exhibiting many interesting bio- 

 logical features. By far the greater proportion are aquatic creatures, 

 actively swimming about in stagnant waters, sometimes in great 

 numbers, and, as we are told by Mr. Slater,* helping to make the water 

 more foul, not, as is usually supposed, cleansing it. "The excreta," 

 he says, " of the creatures contains, in fact, a powerful ferment." 

 Not only are the aquatic forms freshwater, but marine also. Agassiz 

 says that " The larvos of a species of fly {Chirojiomus) is quite common 

 off shore from our northern coasts " (America).! Another American 

 species, C. ocea?iiais, is found at the depth of twenty fathoms. 

 Packard also records the presence of larvDs and pupse of Chironomi 

 in the salt water of Clear Lake, California. I have myself taken 

 Chironomi larv» in pools left by the ebbing tide amongst the green 

 algje on the Guernsey coast, but was not successful in rearing them. 



Then there are saprophytic forms, those feeding upon excreta 



{C. \Orthocladius\ stercorarius), and terrestrial forms living beneath 



the bark of trees {Ceratopogon bipunctafus). The larvse are often 



popularly called " blood worms," on account of their bright red hue. 



These blood worms may nearly always be found in stagnant water, 



especially in butts holding rain water. One of the most abundant 



and typical is Chironomus plumosus, which we will examine in 



detail. 



* " Entomologist," p. 89. 1879. 



f " Cruises of the Blake," vol. i., p. 179. Harvard Bulletin, xiv., A. Agassiz. 



