222 
constantly coming, rattling directly down on the streets 
or smashing against the iron masts or the lanterns them- 
selves, so that heaps of killed or badly wounded insects 
were seen round about. Thousands of the Belostomas 
were trampled under foot or crushed under the wheels 
of the vehicles. As I the next forenoon took a walk 
around in the streets, I still met with plenty of crawling 
and struggling Belostomas and accumulated dead bodies 
of the straying insects. 
How long a distance the Belostomas are able to fly 
in one night, it may not be easy to settle, but one may 
be on the safe side in maintaining the opinion that the 
whole number of individuals have come from the ‘nearest 
environments of the large city. Thus we come to the 
conclusion that the Belostoma annulipes is exceedingly 
common in the districts round Buenos Aires, a conclusion 
we would hardly arrive at by collecting the species in 
the ordinary way. Something like might be the case in 
other districts of South America and perhaps also with 
other species of the genus in other parts of the world. 
11. On Largus rufipennis Lap. 
The above named hemipteron is exceedingly abundant 
on the bushy Senecio mendocinus along the lower pre- 
cordilleras in the western parts of the Province of Men- 
doza. I have often found this plant crowded by an im- 
mense number of the said species, at the same time by 
imagos and larve and nymphs as well. Various branches 
of the plant were in fact not rarely so thickly covered 
with the insects that black spots or stripes in the yellow- 
green top could be seen at a long distance. In the 
district here treated of, nearly all fully developped speci- 
mens were black, with only side margins of hemelytra 
(and sometimes also of pronotum very narrowly) clear 
red. Specimens with disk of hemelytra more or less red 
were seldom met with. As far as I have learned the red 
