Daytime/midday butterfly flurries along trails invariability are attributed
to hackberry caterpillar butterflies. Outbreaks of hackberry butterflies are
sporadic and unpredictable. While hackberry butterflies are present every
year and often go unnoticed, “outbreaks” may cause concern.
Exact reasons to explain outbreaks are unknown. An often-cited reason to explain them is the mildness or severity of the previous winter. This breaks down, however, if one looks at a relatively limited geographical area
experiencing a spate of hackberry butterflies, against other areas which
experienced the same winter conditions —- which begs the question, “Why here and not there?”
The definitive work done by C. V. Riley in Missouri (1874) documented that
hackberry butterflies produced 2 generations per year, with the larvae
emerging from the eggs of second generation moths being the overwintering
form. Based on this, there would be little reason not to expect the same 2
generation scenario in Kansas. So what is the commotion about regarding
hackberry caterpillar butterflies? It is the butterfly themselves, as well
as the impact of larval activities.
The presence of the larvae precedes that of the butterflies. The head of the
larva has an interesting look: a black horned appearance.
In the absence of people, hackberry caterpillars go about their business
without causing concern. However when people decide to “invade” the domain
of hackberry caterpillars, a couple of situations occur. First, if
picnicking beneath hackberry trees in which caterpillars are feeding, the
rain-of-fecal pellets can be unappetizing.
Second, after caterpillars have completed their feeding up in the canopy of
hackberry trees, they descend to the ground in search of a site in which
they will pupate. This stream of caterpillars (again in the presence of
people) may be disconcerting.
Tremendous numbers of larvae translate into eventual tremendous numbers of
butterflies. Thus, the “nuisance factor” continues upon completion of
pupation and the emergence of the “new” butterflies.
By: Bob Bauernfeind