Outline of Quino Recovery Plan - The Xerces Society

The two most important factors affecting the suitability of hostplants for Quino
checkerspot oviposition are exposure to solar radiation and phenology, (timing
of the plant’s development). Quino checkerspots deposit eggs on plants located
in full sun, preferably surrounded by bare ground or sparse, low vegetation.
Plants shaded through the midday hours (1100 to 1400) or embedded in taller
vegetation appear to be less likely targets for oviposition, probably because of
high temperature requirements of developing larvae (Weiss et al. 1987, 1988;
Osborne and Redak 2000). Primary hostplants must remain edible for
approximately 4 weeks after eggs are laid (2 weeks for egg maturation and 2
weeks for larval feeding) (Singer 1972, Singer and Ehrlich 1979). Areas with
hostplant populations that do not remain edible for sufficient time after
oviposition can not provide suitable habitat that season. Adult female butterflies
are adept at selecting those plants that receive adequate sunshine and will remain
edible the longest (McKay 1985, Parmesan 1991, Singer 1994, Parmesan et al.
1995).
Euphydryas editha egg clusters typically contain 20-150 eggs (M. Singer, C.
Parmesan, and G. Pratt, pers. comm.). Destruction of eggs by predators and
physical disturbance can be substantial. Even so, it would be unusual for an
individual Plantago plant to support an entire larval cluster to diapause.
Normally pre-diapause larvae consume the plant on which they hatch, and then
migrate in search for new plants. Their ability to search is quite limited,
especially prior to the third instar. First and second instar larvae can find hosts
within 30 centimeters (1 foot) of their original host plant. By mid-third instar,
larvae can find hosts up to 1 meter (3.3 feet) away (G. Pratt, pers. comm.).
Therefore, high local host density is necessary for high larval survival, but
hostplants must occur in sufficient open areas with high solar exposure (Osborne
and Redak 2000). Where secondary hosts are nearby, the amount of primary
host that is needed may be reduced, but must be sufficient for larvae to reach a
size at which they can disperse to the secondary host.
Secondary larval hosts may be important both before and after diapause. Some
metapopulations of this subspecies may be dependent for persistence on
secondary hosts, but thriving Quino checkerspot metapopulations in Baja
California have persisted for long periods with no other possible host but
Plantago spp. (C. Parmesan and M. Singer, pers. comm.). Typically,
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