Outline of Quino Recovery Plan - The Xerces Society

The life cycle of Quino checkerspot (Appendix I) typically includes one
generation of adults per year, with a 4- to 6- week flight period beginning
between late February and May, depending on weather conditions (Emmel and
Emmel 1977). If sufficient rain falls in late summer or early fall, a rare second
generation of reduced numbers may occur (Mattoni et al. 1997). Females are
usually mated on the day they emerge from pupae, and lay one or two egg
clusters per day for most of their adult life. Adults live from 10-14 days,
however, adult emergence from pupae is staggered, resulting in a 1- to 2-month
flight season. Peak emergence in most butterfly species (and probably for Quino
checkerspots as well) occurs shortly after the beginning of the flight season,
usually in the second week (Zonneveld 1991). Eggs deposited by adults on
hostplants hatch in 10- 14 days.
The periods between molts (shedding skin) are called instars. Larvae that hatch
from eggs are in the first instar, and may undergo as many as 7 instars prior to
pupation. During the first two instars, prediapause larvae cannot move more
than a few centimeters and are usually restricted to the plant on which the eggs
were laid (primary hostplant species). Prediapause larvae spin a web and feed
gregariously. Webs are fairly conspicuous and associated with visible feeding
damage to the plant. During the third instar (about 10 days after hatching),
larvae are able to move among individual hostplants. Third instar larvae usually
wander independently in search of food, and may switch from feeding on the
plant on which they hatched to another plant of the same species, or another
hostplant species (secondary hostplant). During development, the hostplants
age, eventually drying out and becoming inedible. At the time of hostplant
senescence, if larvae have accumulated sufficient reserves, they are able to enter
diapause. Larvae have been observed entering diapause in the lab as early as
second instar, and surviving to the next season (K. Osborne and G. Pratt, pers.
comm.)
Diapause is a low-metabolic resting state that enables larvae to survive for
months during the summer without feeding. While in diapause, larvae are much
less sensitive to climatic extremes and can tolerate temperatures from over 49
degrees Celsius (120 degrees Fahrenheit) to below freezing (M. Singer, pers.
comm.). The larval exterior, or skin, is distinctive during diapause, becoming
much blacker with denser “hairs” (setae) than earlier instars (Appendix I).
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