296 



THE GYPSY MOTH. 



followed by a hot wave, during which a thermometer, ex- 

 posed to the direct rays of the sun at Maiden, reached a 

 temperature of 112° F. This extremely hot weather caused 

 a part of the eggs in this colony to hatch, thus giving rise to 

 a second brood, although in no case was the hatching com- 

 plete, as only a few eggs (one to twenty-five) hatched from 

 a cluster. Eggs brought to the insectary, and kept at an 

 average temperature of 70°, gave rise to a few caterpillars, 

 from time to time, for more than a month. 



A number of the caterpillars from this second brood were 

 collected and sacked in on a small red oak tree, and others 

 were taken to the insectary and fed daily. At the time of 

 this writing (Dec. 5, 1895) a part of the latter have pupated. 

 Careful observations were made upon the caterpillars sacked 

 in on the tree, and also upon those which were feeding under 

 natural conditions in the colony. In neither case were they 

 found to thrive in a normal manner, and with cooler weather 

 and frosty nights they gradually died, until none were left. 

 Those which survived longest had nearly all entered the 

 second molt. The caterpillars reared at the insectary did 

 not show as much strength and vigor as those which hatched 

 normally in the spring, and over seventy-five per cent, of 

 them died before reaching the fifth molt. 



While this is the only positive record of a second brood 

 of the gypsy moth in this country, it is presumably true that 

 in some cases egg-clusters may have partly hatched in the 

 fall of previous years. Any egg-cluster taken in the field, 

 which possesses marked peculiarities, is usually sent to the 

 insectary for examination, and many of the clusters thus sent 

 in during the winter and spring ot 1894-95, were found to 

 contain empty egg-shells. The size and appearance of the 

 holes in the shells indicated that it was not the work of mites, 

 since they eat out a ragged, irregular opening, while the hole 

 left by the exit of the young caterpillar has a more regular 

 outline, and varies from a small circular aperture to a nar- 

 row band eaten around the entire periphery of the shell. 

 After studying a number of these egg-clusters during the 

 spring of the present year, Mr. Kirkland suggested that 

 fall hatching would best explain the occurrence of the empty 

 egg-shells ; but at that time there was no positive evidence 



