Aulacidea podagrae (Bassett, 1890)

Nomenclature: Aulax podagrae Bassett, 1890

Feeds on: Induces galls on Lactuca canadensis L.

Distribution: United States: District of Columbia, Illinois, Kansas, New York, Ohio,Pennsylvania, Virginia

Aulacidea podagrae

Knotty enlargements scattered along stem at bases of leaves. On Lactuca canadensis.

[Photo caption]

352. On Lactuca canadensis. The adults emerged the first week in June (Chi); in May (VA).

Aulacidea podagrae
Lettuce node gall wasp

Hosts: Biennial lettuce (Lactuca biennis) and Florida lettuce (L. floridana).

Gall location: These galls occur throughout the stem, occasionally in multiple disjunct areas.

Description: Highly variable. Generally present as lumpy, amorphous galls jutting outwardly from the stem. Sometimes, they appear as smaller, more-isolated galls rather than larger, more-confluent swellings. They may be single-chambered or have many chambers depending on the individual gall’s shape, size, and structure. Usually brown and rough outwardly with fleshy green areas between apparent nodes.

Range: This gall is known throughout the Eastern United States, from Pennsylvania south to Virginia and west to Kansas. It is likely underreported and probably occurs in additional areas.

This species was originally described in association with Canada lettuce (Lactuca canadensis), but despite substantial recent sampling, it has only been successfully found on biennial lettuce (L. biennis) and Florida lettuce (L. floridana). The original description does mention that the host plant may have been misidentified, further enabling this possibility. The wasps inducing galls on Florida lettuce may prove to be a species distinct from those on biennial lettuce as there are some differences in gall appearance between the two host plants.

Aulacidea podagrae (Bassett)

Aulax podagrae BASSETT

Gall. (Plate XXV, Figs. 1-4.) In the pith of the stalks of wild lettuce (Lactuca canadensis). Polythalamous, sometimes causing a swelling of the stalk.

Habitat: Canada; New England and Middle States, south and westward.

The adult is closely allied to A. tumida, but differs from this species by being darker, and by the more evenly wrinkled thorax and more rugulose scutellum. The gall varies from small pits in the pith of the stalk without any traces of swellings externally, to swellings measuring from 10 to 300 mm. in length and from 10 to 60 mm. in diameter.