THE CHITRONOMID. 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 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 Corynoneura, Diamesa, etc., are scantily 
represented. In Africa large swarms of Chironomid 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. 
Larve of Chironomt. 
The larvze 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 larvze of a species of fly (CAironomus) is quite common 
off shore from our northern coasts ” (America).; Another American 
species, C. oceanicus, is found at the depth of twenty fathoms. 
Packard also records the presence of larve and pupz of Chironomi 
in the salt water of Clear Lake, California. I have myself taken 
Chironomi larvze in pools left by the ebbing tide amongst the green 
algee 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 bipunctatus). ‘The larve 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. 
7 ‘* Cruises of the Blake," vol, i., p. 179. Harvard Bulletin, xiv., A. Agassiz. 
