Grapholita interstinctana

Status

NATIVE

DOMESTIC SURVEY

Taxonomy

Grapholita interstinctana (Clemens) (Tortricidae: Olethreutinae: Grapholitini)

Common names: clover seed caterpillar, clover head caterpillar

Synonyms: distema (Grapholitha), scitana (Dichrorampha)

Adult Recognition

FWL: 4.0–6.0 mm

Forewings are dark brown with a single pair of white dorsal strigulae per wing and four pairs of white costal strigulae. The ocellus is reduced to a silvery-blue bar. The male lacks a forewing costal fold. The hindwings are brown with a white fringe.

Male genitalia are characterized a rudimentary uncus and by the valvae, which have a straight costal margin and a V-shaped ventral invagination at the neck. Female genitalia are characterized by lateral sclerotizations in the ductus bursae and the absence of signa in the corpus bursae. 

Larval Morphology

The following account is summarized from MacKay (1959)MacKay (1959):
MacKay, M. R. 1959. Larvae of the North American Olethreutidae (Lepidoptera). Canadian Entomologist, Supplement 10: 1-338..

Mature larva approximately 5.0–6.0 mm in length; width of head 0.7–0.8 mm; head yellowish brown with black pigmentation in ocellar area; prothoracic yellowish brown with some brownish pigmentation; body pale yellow, legs concolorous; pinacula moderate in size, but concolorous and inconspicuous; anal fork absent; SV group on A1, 2, 7, 8, 9 typically 3:3:1(2):1:1.

Detailed figures of larval chaetotaxy are available in MacKay (1959)MacKay (1959):
MacKay, M. R. 1959. Larvae of the North American Olethreutidae (Lepidoptera). Canadian Entomologist, Supplement 10: 1-338..

Similar Species

Adults appear similar to many other species of Grapholita. In eastern North America, G. fana is most similar, but the two species are easily distinguished by the larger ocellus in G. fana. Genitalia of the two species are different: males of G. fana lack the invagination on the ventral surface of the valve and females possess a pair of short signa.

Distribution

Grapholita interstinctana is distributed in eastern North America from Maine to Alberta, south to Missouri.

Biology

The following account is summarized from Wehrle (1924)Wehrle (1924):
Wehrle, L. P. 1924. The clover-seed caterpillar. Cornell University Agricultural Experiment Station Bulletin. 428. 34 pp..

Grapholita interstinctana completes 2–3 generations per year. Adults fly from late May to September.

Larvae feed on seeds in the heads of clover (Trifolium spp.); usually one larva is present per flower head. Overwintering occurs as a mature larva and pupation occurs in the spring.

In the early part of the 20th century, G. interstinctana was considered a significant pest of clover (Folsom 1909Folsom 1909:
Folsom, J. W. 1909. Clover seed-caterpillar, pp. 133-137. In : The insect pests of clover and alfalfa. University of Illinois Agricultural Experiment Station Bulletin 134.). Larvae have also been reported feeding on sunflower (Asteraceae).

Plant Associations

View full screen host table here

Links

Additional photos and a distribution map of this species in North America are available at Moth Photographers Group.