SAMPLING WESTERN HEMLOCK LOOPER PUPAE (LEPIDOPTERA: GEOMETRIDAE) USING BURLAP TRAPS

Burlap wrapped around western hemlock, Tsuga heterophylla (Raf.) Sarg., trees at breast height was used to trap pupae of the western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst). The number of pupae in the traps was highly variable and was not related to tree diameter or the surface area of the trap. There was a significant relationship between the number of viable pupae per trap and the number of healthy western hemlock looper eggs subsequently laid on lichen in the trees. Sample size requirements are presented.

CHAETOPHLEPSIS NASELLENSIS, A DIPTEROUS PARASITOID OF THE WESTERN HEMLOCK LOOPER (LEPIDOPTERA: GEOMETRIDAE)

Preserved material from 1962 field studies provided information on the habits and morphology of the tachinid parasitoid Chaetophlepsis nasellensis Reinhard. Parasitization of the larvae of the western hemlock looper, Lambdina fiscellaria lugubrosa (Hulst), continues over a 30- to 40-day period. Maggots issue from the host larvae and drop to the ground to pupate. The pupae normally overwinter, with adults emerging the following spring or summer. The early first-instar larva differs markedly from the late first-instar. The three instars can be distinguished on the basis of body length and the structure and form of the buccopharyngeal apparatus. The first and third larval instars and the puparium are distinctive enough to permit easy identification during studies of the western hemlock looper and associated loopers.

REPRODUCTIVE BIOLOGY OF LAMBDINA FISCELLARIA LUGUBROSA (LEPIDOPTERA: GEOMETRIDAE)

Calling by newly emerged female Lambdina fiscellaria lugubrosa (Hulst) began the first evening and commenced 15 h after the onset of light in nature and in a 14L:10D photoperiod regime in the laboratory. Copulation began 0.5 to 1.5 h later, and moths remained in copulation an average of 3.45 h. The internal reproductive system is typical of ditrysian-type Lepidoptera. Mating usually resulted in the transfer of a single, spheroid spermatophore with a long collum. The spermatophore was placed in the bursa copulatrix in such a position that spermatozoa could leave through the aperture into the ductus seminalis. The greatest mating success occurred between 2- to 4-day-old males and females up to 4 days old. Maximum oviposition occurred on the day after mating. Numbers of eggs maturing and being laid were increased after mating. Mean longevity of mated and unmated females in the laboratory was 18.1 and 20.8 days, respectively. Mating success was greatest at a 6:1 male to female sex ratio, and progressively less at a 1:1 and 1:6 sex ratio. Males mated only once in a 24-h period, but were capable of multiple mating. Females usually accepted one spermatophore but occasionally up to three were found.

SEX ATTRACTION AND COURTSHIP BEHAVIOR IN LAMBDINA FISCELLARIA LUGUBROSA (LEPIDOPTERA: GEOMETRIDAE)

Calling by female Lambdina fiscellaria lugubrosa (Hulst) occurred when terminal abdominal segments 8–10 were protracted, exposing an enlarged region in the intersegmental membrane between segments 8 and 9. Histological examination of this region disclosed paired glands situated ventrolaterally in the eighth segment. The glands were presumed to be pheromone glands, and differ from those described for other Lepidoptera, in their paired structure and ventrolateral position. More males were attracted to traps containing virgin females than to empty control traps, but only during the first half of the moth flight. Board and yellow carton sticky traps were superior to 3M and white carton traps. Behavioral observations suggested that the sex pheromone may serve as an excitant as well as, or instead of, an attractant, stimulating the male to searching activity.