A MIGRATING ARMY OF SCIARID LARVAE 
IN THE PHILIPPINES 
By Charles T. Brues 
Harvard University 
On the morning of June 15, 1949 we witnessed a mass 
migration of fungus-gnat larvae in the rain-forest zone of 
Negros Island at an altitude of about 4,000 feet. Close to 
a temporary shelter in which we were housed, my wife 
noticed a strange crawling object moving over the wet, 
muddy soil. Closer examination at once disclosed that this 
was an irregular, band-like mass of small dipterous mag- 
gots such as have been noted from time to time in scat- 
tered localities in the holarctic region. Originally known as 
Heerwiirmer in Europe and as snake-worms in the United 
States, these when reared, have always proved to be mem- 
bers of the genus Sciara. Sciara is cosmopolitan in distri- 
bution and many species are known, but it appears that 
only a very few ever indulge in migrational processions. 
In the present instance, the mass of larvae was moving 
slowly in a very irregular band about a foot in length, less 
than an inch in width and layered to a depth of about half 
an inch. As has been described in some previously observed 
cases, the individual larvae were moving on the slimy bodies 
of their fellows so that progression is accomplished by the 
forward motion of those on the top, while those at the rear, 
as they are uncovered, move with a sort of superficial, belt- 
like, rolling motion over the cramped individuals in the 
lower layers. Thus, the mass moves onward, but the lar- 
vae are continually changing position with reference to one 
another. 
It had been raining during the night and the mountain 
was intermittently in the clouds. The wet soil was marked 
with numerous foot-prints and with a shallow drainage 
ditch to guide water away from the shelter, there was thus 
little opportunity to steer a straight course and the move- 
ment was very erratic, although consistently in the general 
direction of the drier ground under the shelter. 
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