▁Pe hr ▁Kal m , ▁a ▁Swedish ▁natural ist ▁visit ing ▁Pennsylvania ▁and ▁New ▁Jersey ▁in ▁ 1 7 4 9 ▁on ▁beh alf ▁of ▁his ▁nation ' s ▁government , ▁observed ▁in ▁late ▁May ▁one ▁such ▁emer gence . ▁When ▁reporting ▁the ▁event ▁in ▁a ▁paper ▁that ▁a ▁Swedish ▁academic ▁journal ▁published ▁in ▁ 1 7 5 6 , ▁Kal m ▁wrote : ▁The ▁general ▁opinion ▁is ▁that ▁these ▁insect s ▁appear ▁in ▁these ▁fant astic ▁numbers ▁in ▁every ▁sevent e enth ▁year . ▁Meanwhile , ▁except ▁for ▁an ▁occas ional ▁one ▁which ▁may ▁appear ▁in ▁the ▁summer , ▁they ▁remain ▁under ground . There ▁is ▁considerable ▁evidence ▁that ▁these ▁insect s ▁appear ▁every ▁sevent e enth ▁year ▁in ▁Pennsylvania . ▁▁ ▁Kal m ▁then ▁described ▁documents ▁( including ▁one ▁that ▁he ▁had ▁obtained ▁from ▁Benjamin ▁Franklin ) ▁that ▁had ▁recorded ▁in ▁Pennsylvania ▁the ▁emer gence ▁from ▁the ▁ground ▁of ▁large ▁numbers ▁of ▁cic adas ▁during ▁May ▁ 1 7 1 5 ▁and ▁May ▁ 1 7 3 2 . ▁He ▁noted ▁that ▁the ▁people ▁who ▁had ▁prepared ▁these ▁documents ▁had ▁made ▁no ▁such ▁reports ▁in ▁other ▁years . ▁Kal m ▁further ▁noted ▁that ▁others ▁had ▁informed ▁him ▁that ▁they ▁had ▁seen ▁cic adas ▁only ▁occasionally ▁before ▁the ▁insect s ▁appeared ▁in ▁large ▁sw ar ms ▁during ▁ 1 7 4 9 . ▁ ▁He ▁addition ally ▁stated ▁that ▁he ▁had ▁not ▁heard ▁any ▁cic adas ▁in ▁Pennsylvania ▁and ▁New ▁Jersey ▁in ▁ 1 7 5 0 ▁in ▁the ▁same ▁months ▁and