The Palmp:k-W()rm. 99 



scorched by fir3. Apple-trees aiid oaks seemed to suffer most, but 

 all other trees and shrubs were more or less infested with these 

 worms at this time. On jarring or shaking a tree, hundreds would 

 instantly let themselves down fi-om among the leaves, by fine 

 threads like cobwebs, some dropping to the ground, others remain- 

 ing suspended ir tlie air. Persons at work at this time upon 

 potatoes or other field crops growing in orchards would have num- 

 bers of them crawling everywhere over tlieir clothes. ^ ^' * 

 The crop of fruit for the year was everywhere destroyed." 



^A'iting in 1S5G, Fitch states that tlie year following the excessive 

 ravages of the palmer-worms, " it was universally expected, in June, 

 that these worms would again appear, but tlie month passed away 

 and no traces of them were anywhere to be seen. They could 

 readily be found, however, on searcliing upon the leaves of the 

 apple-trees, but Avere no more common than several other kinds of 

 worms in the same situation. Last year, 1S55, they were quite rare, 

 a very few specimens only having presented themselves to my 

 notice. The present year tliey have been much more abundant, 

 and in gardens in the city of Albany I observed a number of fruit 

 trees the leaves of which had been badly eaten by them." 



Thus, soon after its sudden appearance and excessive ravages in 

 1853, the insect ceased to attract attention, and did not again pose 

 as an injurious insect for fifty-seven years, or until 1900. 



AYe can not satisfactorily explain these remarkable "ups" and 

 " downs " in the life-history of the palmer-worm during the past 100 

 years, during which period it has been noticeably injurious only 

 three times. It has natural enemies which doubtless are a factor in 

 reducing the numbers of the insect below the danger limit, but 

 probably climatic conditions are more potent factors. In this con- 

 nection it is worthy of note that in Deane's account of the out- 

 break in 1791, he states that "the spring which preceded their 

 appearance had been remarkably dry, both in April and May." 

 And Fitch states that the weather in 1853 had been remarkably dry 

 and hot for some time previous to the advent of the insect. The 

 spring months of 1900 were also much drier and hotter than usual. 

 Evidently, then, extreme dry and hot weather in the spring are very 

 favorable for the development of the insect. 



