Snakeweed Insect Collection
Some Snakeweed Insects
One of the most important of the insects attacking snakeweed is the long-horned beetle Crossidius pulchellus. The larvae of this beetle bore into the crown and tap root of the plant, usually destroying it. They attack only mature plants, however, and the adult beetle (seen here) may serve as a pollinator, as it frequents the blooming plants in the fall.
- (Photo by David Thompson)
The larva attacks the root and leaves a characteristic bore hole through the center of the root. There is usually only one larva per root.
The clerid beetle, Enoclerus coccineus, is a major predator of snakeweed root-boring insects, especially Crossidius pulchellus. The larvae of this predator are bright pink in color and on at least one year were found more offten than Crossidius pulchellus is the roots.
More Snakeweed Insects
Some snakeweed insects can be very colorful, as is the foliage-feeding caterpillar of Cuculia sp., a noctuid moth. While these insects do not ever seem to be so numerous as to damage snakeweed stands, they do feed on the plants.
The larvae of the moth family Geometridae are the familiar "inch-worms". This is a common geometrid that feeds on woody snakeweeds.
The tortricid leaftier, Synnoma lynosyrana, can be responsible for up to 50% seed destruction on branches it ties up. The feeding of the caterpillar may severely stress the plants, opening them to attack by such root-borers as Crossidius pulchellus.
A major natural enemy of the snakeweed leaftier is the ichneumonid parasitoid Glypta albitibia.
The snakeweed, or red-kneed grasshopper, Hesperotettix viridis, can be a major player in the natural control of woody snakeweeds. A density of only a few grasshoppers per plant can completely defoliate snakeweed and result in a total destruction of the seed crop for that year.
The snakeweed grasshoppers also has natural enemies, such as this asilid fly
- (Photo by David Thompson).
The snakeweed bud weevil, Anthonomus tenuis, appears to favor broom snakeweed over the related thread-leaved snakeweed for oviposition. The larvae of this beetle can destroy a significant amount of the seeds in a flower head.
The leafbeetle, Monoxia pererbula, can cause serious damage to snakeweed, under certain conditions.
Unfortunately the plants usually recover, although their seed production is destroyed for that year.