LIFE HISTOKY AND CONTEOL OP HOP PLEA-BEETLE. 47 
the size of a pin head were observed in the nettle leaves and these 
beetles continued to feed until spring. The majority of the beetles 
were active whenever the cage was in the light and the temperature 
above 50°. They became inactive only when darkness approached or 
the temperature fell below 40°. The beetles were not observed to 
seek hibernating places when artificially emerged, unless conditions 
were unfavorable to activity. When put in a cool, dark place many 
of the beetles entered hollow vine stubs and pieces of corrugated 
paper which were placed in the cage for this purpose. Some, how- 
ever, were content with the cloth top and the glass sides of the cage 
for a hibernating place. 
Natural emergence. — On March 9 four beetles were seen crawling 
around on the sunny side of a trellis pole. These were the first that 
were observed emerging in the field. When warm days became 
more frequent the beetles appeared in numbers and fed upon the 
young nettles. They were very active and were observed copulating 
during the warmer part of the day, but when evening came they 
disappeared from view and did not come out again until the frost 
was all melted the following morning. Although some beetles 
emerged during the warmer days of March, the maximum number 
did not appear until April 15. After this they gradually diminished 
in numbers and by the 10th of May had nearly all disappeared. 
DISEASES. 
FUNGOUS DISEASES. 
Many of the beetles that were found dead in the hollow vine-stubs 
were covered with a white mycelium. When these beetles were 
placed in a moist chamber Penicillium glaucum and the hop-mold 
Sphcerotheca castagnei developed. 
No other fungous growths were observed by the writer, but Dr. 
C. S. McKee, of Vancouver, British Columbia, in a letter regarding 
some of his experiments with the hop flea-beetle, mentions a fungous 
disease in the following words : " Before they began to die they were 
distinctly less active, and even before death some of them could be 
seen to have a fungous or mouldy growth on them, particularly under 
the wings." Doctor McKee does not state what this fungus was, and 
it is quite possible that it was a Penicillium, as was found on the 
beetles in the field. Although Penicillium is known, under some 
circumstances, to become parasitic, the probability is that the bee- 
tles died from some other cause and that the fungus entered as a 
saprophyte. 
