Early and Late Dates, Each Year, 2008-2016

The spreadsheet at the first link below lists each year’s early and late dates for all 106 butterfly species we have found so far in South Jersey, 2008-2016.

The extreme dates are in color:

Green = earliest date we have recorded so far.
Orange = latest date we have recorded so far.
When dates are duplicated year to year (= a tie), both dates are highlighted.

Blue = first reports of a species that are problematic.  (See “A Problem With January Reports” below).

Hit the + sign for easier viewing of the pdf.

Early & Late Dates All Species All Years (corrected Jan 24 2017)

(Thanks to Steve Glynn and Tom Bailey for some corrections to the original post of the spreadsheet. I welcome any others found by other readers.)

Keep at it, everyone.   We have already recorded two species for 2017: orange sulphur and monarch.  Which species will be our 3rd?

Jack Connor

Some notes for especially-interested readers:

Two Changes In The Complete List

One species has been added to our full set:  Hobomok skipper, photographed on May 15, 2010 and added retrospectively.

A New Species for Southern NJ

Southern broken-dash has been added as a hypothetical species (in italics), based on a photograph from Forsythe NWR, ATL, on 7-26-16 (and a couple of other suggestive photos from CMY).

Southern Broken-Dash, A Species To Look For?

A Problem With January Reports

January sightings can be awkward to handle on this chart — with December 31 and January 1 artificially separating “last” and “first” butterflies reported. During warm winters late-flying individuals of some species can live past the New Year. Orange sulphurs are perhaps the most difficult to assess. We could find an orange sulphur on December 31 somewhere and consider it tying our latest-ever record, and find the same individual the next day and record it as the earliest-ever. That is somewhat misleading. Most (all?) are worn and apparently on their last legs. The species usually does not eclose until late March or April in our area. However, according to Art Shapiro (fide Gochfeld and Burger), they occasionally emerge in mid-winter when temperatures are 60+ degrees.

Monarchs also sometimes survive until January — but these individuals are flying too late to reach Mexico and are almost certainly doomed to expire before spring. Calling a monarch seen in January our first of year is clearly misleading, so these are not colored green.

On the other hand, some species frequently over-winter as adults (mourning cloak is the best example, but red admiral, American lady, common buckeye, American snout and one or two others perhaps also live through the winter as adults.) The emergence of these over-winterers in January seems a different kind of phenomenon than the late-flying sulphur or monarch. They are not necessarily on their last legs — and could very well return to their hiding places (or find new ones) and survive to spring and breed then.  These are colored green.

The December 2015 and January 2016 Blueberry Azures:

Even more problematic for our chart are the blueberry azures that emerged in CMY in December 2015 and January 2016. These were all fresh individuals, apparently very recently-emerged. According to David Wright, this species had never been recorded in NJ in either month. One could argue that those December individuals breaking diapause in mid-winter are new early records for our log. In other words, butterflies of 2015 should be considered the first of 2016. That is awkward, however.  Also, they were almost certainly doomed, as were those azures that apparently emerged in early January 2016.  It is almost certain that all expired as more normal winter weather set in during mid-January.

Since the January individuals emerged in 2016, I have decided to call them earliest-ever, following the weak logic that they did emerge in the calendar year.  Anyone with a better way to handle this freakish phenomenon is invited to write to me or Leave a Comment below.


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