Problems in Identification: Flightless Females

In several families of North American moths we find genera of flightless females. In the Lymantriidae which includes the Tussock Moths the entire genus Ogyria has wingless females. Also within this family are a couple of fully-winged females that are apparently too heavy bodied for flight. These include the female of the infamous Gypsy Moth, Lymantria dispar and females of two alpine species in the genus Gynaephora.

  Wingless Female: Live Oak Tussock Moth -- Orgyia detrita

Typical of the Tussock Moth genus Ogyria, females are virtually wingless and absolutely flightless. They eclose full of eggs and ready to mate. By releasing a pheromone they "call" males to them. They are usually ready to lay fertilized eggs shortly after mating. The eggs are laid on the cocoon and may be covered with a foamy protective covering. The entire process from eclosure to egg laying and female death may be completed within 24 hours.

mating - all photos Machele White

egg laden female female, egg mass on cocoon

  Wingless Female: White-marked Tussock Moth -- Orgyia leucostigma

The foamy egg mass is here seen with a little bit of the cocoon appearing behind it. The cocoons are typical found in crevices of trees that have roughly textured bark. But they might also be found on other vertical surfaces such as fences and walls of building. In this instance the female is shown in an unnatural setting. She eclosed from a cocoon that I brought indoors for study and I took her outside for a photograph in sunlight. She laid infertile eggs because I did not provide her with an opportunity to "call" for males.

male - Robert Patterson female - Robert Patterson

egg mass - Robert Patterson

larva - Janice Stiefel
  Wingless Female: Western Tussock Moth -- Orgyia vetusta

Joyce Gross found numerous cocoons and larvae of this species at the University of California at Berkeley. Her paper showing parasitoid activity in this population may be seen here. The caterpillars in Joyce's study were feeding on leaves of a Coast Live Oak. Last instar caterpillars tend to disperse prior to entering the pupation stage. In this case many of them attached their cocoons to walls of one of the nearby university buildings.

mating pair, reared indoors - Joyce Gross female, hair-covered egg mass on cocoon - Joyce Gross

  Flightless Females: Members of the Geometridae

Within the large family Geometridae there are several genera in which females have very reduced wings. Some appearing to be virtually wingless. The genus Phigalia is sometimes referred to as the half-wing moths and one of its members is indeed known by that common name. Since females can't fly (they can crawl) dispersal in these species takes place mainly in the caterpillar stage.

The Half-wing Moth - Phigalia titea
Anthony W. Thomas - NB

The Half-wing Moth - Phigalia titea
male - Machele White - FL
Wooly Gray Moth - Lycia ypsilon
Randy Newman - NC
Linden Looper Moth - Erannis tiliaria
Larry Line - MD
  Flightless Females: Members of the Psychidae

Another interesting family with flightless females is the Psychidae or Bagworm Moths. With only about 25 member species in North America they are relatively small and poorly known although widely distributed. Caterpillars build silken cases about them, adorned with needles, or pieces of bark or leaves from the tress they inhabit. These cases provide protection for feeding larvae and become pupation chambers, and females, who are usually wingless (or have tiny vestigial wings), in most cases never leave the cases. Males, who can fly and do leave the case at eclosion, find females by keying in on pheromones release to attract them. Mating takes place when a male inserts his abdomen into an opening in the female's case (without ever actually seeing her). Eggs are laid in the case and, upon hatching, larvae disperse to build their own cases and continue the life cycle. Upon leaving the case a male may leave an exuvium, remains of the last larval skin, dangling from the exit port as seen at right, below.

Psyche casta
John Himmelman - CT

Abbot's Bagworm - Oiketicus abbotii
Jeff Hollenbeck - FL
Exposed Case, Bagworm Larva
Charles Lewallen - OK
Evergreen Bagworm male case
Charles Lewallen - OK

MothTalk/MothTalk013.htm -- 01/15/2007