Iowa Insect Information Notes

Hummingbird Moths

Hummingbird Moths

There is so much to enjoy in late summer.  One of my favorites is the large dark moths that look and act like hummingbirds, feeding on nectar from flowers around dusk.  Favorite flowers include deep-throated blossoms such as petunias and hosta blooms.

The moths in question are large and about the size of a hummingbird.  There the physical resemblance ends.  However, it is remarkable how much the moths behave like hummingbirds.  They hover in mid-air and flit from one flower to the next.  If you don’t look closely at the dark color and the antennae at the front of the head, you can be easily fooled into believing these really are hummingbirds!

The name hummingbird moth is a nickname used for several different species of sphinx moths.  Sphinx moths, also known as hawk moths, are from the family Sphingidae.  These are medium to large-sized moths with a robust body and narrow, elongate front wings. The wings have the shape of a wide, flat triangle ending in an acute angle at the farthest point.  Sphinx moths may have a wingspread of up to 6 inches though a more common size in Iowa is a 2 to 4.5 inch wingspan.  There are approximately 125 different species of sphinx moths in the U.S. and Canada.

 Sphinx moths are strong fliers with a very rapid wingbeat.  They are capable of hovering in mid air for extended periods and flying just in front of flowers as they sip nectar through their extended proboscis.  A tiny amount of nectar is withdrawn during a brief visit to each flower.

 The well-developed proboscis of hummingbird moths is an extendable, beaklike hollow tube or tongue that may be several inches in length and often as long as or longer than the moth’s body.  When not in use the proboscis is coiled against the underside of the head.  The tightly spiraled proboscis is extended and held stiff by internal fluid pressure as the moth reaches for the nectar supply at the base of flowers.  When the moth is done feeding, muscles coil the proboscis back into resting position.  The rolling and unrolling action of the proboscis can be compared to the movements of a party noisemaker.

 The most commonly observed hummingbird-like moth is the whitelined sphinx, Hyles lineata, so named for the broad white stripe running diagonally to the outer tip of each front wing.  This is a stout-bodied, brown moth with a wingspan of 2.5 to 3.5 inches.  The delicate pink coloration of the hind wings is visible when the moths are hovering at flowers.  Whitelined sphinx moths are as likely to fly during the day as they are at twilight.

Hummingbird moths are completely harmless.  Their nectar-sipping activity causes no harm to the flowers.  Even the hornworm caterpillar stage of most hummingbird moths is of relatively minor importance.  Treatment is not warranted.  Just enjoy the show!

 

Hummingbird Moth
Tobacco hornworm moth visiting a petunia. Photo by Diane Nelson.

 

Updated 08/30/2007 - 1:40pm