INSECTS AND PLANTS 65 



cross-breeding of allied species, hoped to produce an insect 

 that would be more resistant to disease. His charges em- 

 braced a variety of species from many countries, and among 

 them the European gipsy moth. According to one version, 

 the eggs of one of these moths were blown from his study 

 window. Another account says that the caterpillars crawled 

 out. Whatever may be the correct story matters little, the 

 tragedy lies in the fact that Porthetria dispar was at large 

 in the woodlands neighbouring on Medford, Massachusetts. 

 Though the accidental introducer of a very serious pest that 

 eventually cost his country thousands of dollars, in an 

 attempt at eradication, credit must be given to the Professor 

 for his foresight in at once giving notice that a dangerous 

 insect was at large ; but his warning fell on deaf ears. 

 Probably the people took no notice, because, at first, the 

 insects were seldom seen; they increased very slowly by 

 reason of the fact that they were accommodating them- 

 selves to the severe climate to which they were un- 

 accustomed. Porthetria dispar remained very much in the 

 background, or apparently so, for about a dozen years, when 

 some of the trees about Medford were defoliated by cater- 

 pillars, whose identity was not at the time revealed. An 

 energetic but unavailing onslaught was made on the pest, 

 for, by the summer of 1889, "it had multiplied to such an 

 extent as to become a notorious pest. Its numbers were so 

 enormous that the trees (woodland and fruit) were com- 

 pletely stripped of their leaves; the crawling caterpillars 

 covered the side-walks, the trunks of the shade trees, the 

 fences, and the sides of the houses, entering the houses, and 

 getting into the food and into the beds. They were killed 

 in countless numbers by the inhabitants, who swept them 

 up into piles, poured kerosene over them, and set them on 

 fire. Thousands upon thousands were crushed under the 

 feet of pedestrians, and a pungent and filthy stench arose 

 from their decaying bodies. The numbers were so great 

 that in the still summer nights the sound of their feeding 



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