Goldenrod Flower Gall

Tephritidae and the stem and gall boring mordellistena convicta coleoptera.
Goldenrod flower gall. The stem of the goldenrod stops growing but the leaves don t. Gigantea are subject to three different types of stem galls caused by tiny insects that lay their eggs on the plants the larva from the hatched egg then eats its way into the stem. They are mostly native to north america including mexico. Upon hatching larvae eat into the stem whereupon they secrete chemical compounds that trigger the plant s meristem cells to form the gall.
The round stem balls are called galls. Mordellidae provide behavioral ecological and genetic evidence of insect host races that may represent incipient species formed via sympatric speciation. Our studies of the interactions of goldenrod host plants solidago. They are the plant s response to the parasitic goldenrod gall fly eurosta solidaginis.
This results in a tight flower like cluster of foliage. In two cases ball gall and spindle gall the plant then responds to this event by rapidly increasing cell growth around the intrusion enveloping the larva in a woody protective sheathing that not only keeps the. Canada goldenrod solidago canadensi s is an aggressive native plant that is quick to colonize disturbed areas including gardens that many people wish to keep out but it does support a very specific and unique fauna. Most are herbaceous perennial species found in open areas such as meadows prairies and savannas.
After the grub hatches its presence somehow keeps the stem from growing and elongating even though the goldenrod continues to produce leaves. The larva eats the inner tissue and grows but the plant is not harmed. Sometimes as in this photo the stem will continue to grow above the rosette gall but it s much more spindly. Many plant species attract gall makers but goldenrods seem especially alluring to them.
A few species are native to south america and eurasia. Compositae the gall fly eurosta solidaginis diptera. Adult goldenrod bunch gall midges emerge from the galls in the. Goldenrods are a common wildflower painting fields prairies and meadows yellow in late summer.
Goldenrod bunch galls also called rosette galls are the result of an egg being laid in the topmost leaf bud of canada goldenrod solidago canadensis by a midge in the genus rhopalomyia often rhopalomyia solidaginis. Galls are common albeit abnormal plant growths caused by the larvae of certain insects and mites. The female fly lays eggs at the base of goldenrod flower buds. Once the grub of this tiny creature hatches the stem of the goldenrod generally stops growing but keeps producing leaves which bunch up and make a nice hiding place for a midge s larva to grow along with spiders and other midges who may move in.
Late goldenrod solidago altissima with two subspecies and giant goldenrod s. The resulting rosette of leaves provides shelter and food for the midge larva as well as a host of other insects including other midges. Solidago commonly called goldenrods is a genus of about 100 to 120 species of flowering plants in the aster family asteraceae. The goldenrod bunch gall resembles a flower but it is actually a rosette of leaves caused by the entry of a goldenrod bunch gall midge rhopalomyia solidaginis larva into the stem of its host goldenrod species solidago altissima.