Biological Control Agent:  Lobesia euphorbiana (Freyer)

Invasive Plant Species Attacked: Leafy spurge (Euphorbia esula) and cypress spurge (E. cyparriasias). 

Type of agent: Leaf tying moth

Status

Primary

Description and Biology

Adult:

Adults are mottled yellow, brown and reddish coloured. Wingspan is 10 – 14 mm. First generation adults begin to appear in the field by mid June, mating and egg laying begins immediately, occurring mainly at dusk and dawn. There are two generations per year, and possibly three in southern Ontario. Females lay an average of 55 eggs each, which are laid individually onto lower leaf surfaces. Adults live 3 – 7 days.

Egg:

Eggs are translucent yellow and measure 0.77 x 0.62 mm. Eggs are highly fertile and very few fail to hatch.

Larva and pupa:

Young larvae are pale green, and when mature, are almost black. Newly hatched larvae move towards terminal leaf tips and tightly tie leaves with silky webbing. There are normally four instars, head capsule measurements are used to determine each. Up to five instars can occur when food sources are low. Terminal ties yield larger larvae/pupae than lower stems.  Larvae also develop slower on lower lateral shoots than on the terminals. Several larvae can begin in one tie, however, only one completes development. The others are either killed or forced out where they will develop slower with five instars. However, larvae and pupae can exist together in a single tie. When the ties are opened the larvae agitate easily and lose vigour.  They are not cannibalistic unless they become short of food. Larvae prepare for pupation by moving to the leaf tip where they spin a thick web. Fresh pupae are pale green, changing to brown just before emerging. At 21 – 24°C and 16 hour days, pupation is completed in 26 days, therefore, the development from egg to adult (second generation) is completed in 36 days.

Overwintering stage:

The second generation pupae overwinter within folded leaves in soil litter.

Location and effectiveness of attack

Larvae enclose themselves inside tied terminal leaves where they consume the bud and prevent flowering. Repeated heavy attack eventually kills the plant. Vacated ties attract thrips and aphids, creating preferred locations for secondary attack.

Predicted and native habitat

Lobesia euphorbiana prefers sites which are warm to hot during the summer. Complete development requires high temperatures. It inhabits fringe forested areas, tolerating shade. They require active growing plants with high nutrient quality usually found growing in mesic conditions. They do not do well on weak stands growing in poor soils. It commonly establishes near water.

The native range of L. euphorbiana is from south and central Europe to the Ukraine.

British Columbia Experiences

The first release was made in 1990 near Kamloops. Good recovery was found by 1998 and collections commenced. It has been released into and found established in the Bunchgrass, Interior Douglas-fir and Ponderosa pine zones. Ties and larvae have been located in the field from late May to early August which persist after the adults vacate. The density of ties at the established sites appear to fluctuate with the plant vigour.

Collection for redistribution

Not available for general distribution at this time.

Notes

Sometimes gall terminals made by Spurgia esulae will be used by L. euphorbiana.

References

Harris, P. 2005. Classical biological control of weeds established biocontrol agent Lobesia euphorbiana (Freyer). Leaf-tying moth. Govt. of Can., Agriculture and Agri-Food Canada. February 7, 2007. http://res2.agr.ca/lethbridge/weedbio/agents/alobeup_e.htm

Harris, P. and J. Soroka. No date. Lobesia (Lobesides) euphorbiana (Frr.) (Lepidoptera: Uleuthreutinae): a candidate for the biological control of leafy spurge in North America. 36 p.

MFR staff observations and comments

Powell, G. W., A. Sturko, B. Wikeem and P. Harris. 1994. Field guide to the biological control of weeds in British Columbia. B.C. Min. For. Res. Prog.