Actia diffidens Curran, 1933

O’Hara, James E., 2005, A review of the tachinid parasitoids (Diptera: Tachinidae) of Nearctic Choristoneura species (Lepidoptera: Tortricidae), with keys to adults and puparia, Zootaxa 938, pp. 1-46 : 15-17

Actia diffidens Curran, 1933 , Fig. 37

Host records ex. Choristoneura conflictana: Prentice 1955 (SK, MB); O’Hara 1991 (†SK, MB); † Arnaud 1978 (SK, MB); † Huber et al. 1996 ( America north of Mexico). Host records ex. Choristoneura rosaceana: O’Hara 1991 (ON); † Huber et al. 1996 ( America north of Mexico).

This species is an uncommonly recorded parasitoid of Choristoneura species. It is similar in size and appearance to A. interrupta except that wing vein CuA 1 is almost always bare dorsally (only rarely with one to several hairs; veins R 1 and R 4+5 haired as in A. interrupta ; cf. Figs. 12 and 13 ). Actia diffidens is common and widespread throughout Canada and the northern and eastern United States, with scattered records throughout the rest of the United States and Mexico ( O’Hara 1991). The first instar of A. diffidens was figured by O’Hara (1988) and the adult was redescribed by O’Hara (1991) in his revision of the Nearctic species of Actia . The three larval instars, pupa, and puparium were described and illustrated by Prebble (1935).

Prebble (1935) studied parasitism of the tortricid Acleris variana (Fernald) (as Peronea variana ) by A. diffidens in Nova Scotia. He found that adult A. diffidens appeared in June, parasitism of third to fifth instar A. variana occurred from late June to mid July, and fully developed maggots emerged from their hosts and formed puparia from mid July to mid August. Known hosts of A. diffidens are mostly Tortricidae but include a few species of Geometridae , Gracillariidae , Noctuidae , and Pyralidae ( Arnaud 1978; O’Hara 1991).

Figures

FIGURES 37 – 42. Habitus images. 37. Actia diffidens. 38. Actia interrupta. 39. Ceromasia auricaudata. 40. Compsilura concinnata. 41. Cyzenis incrassata. 42. Eumea caesar.

FIGURES 11 – 13. 11. Lateral view of tachinid thorax. 12. Actia diffidens, right wing. 13. Actia interrupta, right wing.