Erynnis icelus

Photo Life History:  Erynnis icelus

Habitat:  Mountain Canyons; Mountain Hilltops

Host Plants:  Salix exigua; Populus tremuloides;  Robinia pseudoacacia.

Suitable Lab Host Plants:  Most willows will work in the lab.

Caring for Live Female Butterflies:  Nectaring techniques

Methods of Female Oviposition:  Erynnis females can be somewhat uncooperative at laying eggs in captivity.

How to Find Eggs:  Look on Host Plants with New Growth  (This is critical.  Eggs turn orange after having been laid.  This makes them a little more conspicuous.  Sometimes females will oviposit on aspen seedlings.)

How to Hatch Eggs:  Consolidate eggs into one container. 

How to Find Caterpillars in the Field: Look for Skipper Nests; Larvae sometimes are found towards the ends of branches near where eggs were laid on new growth. 

Caterpillar setups:  Using the open terrarium or open bucket technique.

Larva to Pupa:  Larva Changes Color before hibernating as mature last instar caterpillar.

How to Find Pupae in the Field:  Extremely difficult since larvae pupate in leaf litter in the spring.

Number of Broods per Year:  1-2; depending upon location.

Overwintering Stage:  Mature Fifth Instar Larva

Overwintering Strategies:  Your Own Backyard.  (Expose larvae to intermittent humidity and some airflow.) 

Post-Hibernation Strategies: Expose post-diapause larvae to warmer temperatures and intermittent humidity.  Larvae will then pupate.

Avoiding Diapause Techniques:  Sometimes larvae will pupate in the fall if reared in the lab.  If they do, they are committed to emerge in the fall and will not overwinter.  This can be more prevalent with E. icelus than other duskywings.

Disease Prevention: Change out host plant and remove frass every four to five days using the open terrarium technique. 

Emergence:  Emergence Container

Field Notes:  Larvae have been found on Populus tremuloides at Farmington Canyon, Davis County, Utah on seedlings right along the canyon dirt road in the late summer/early fall.