Gj. Michels et al., OVERWINTERING SURVIVAL OF 7 IMPORTED COCCINELLIDS IN THE TEXAS HIGH-PLAINS, The Southwestern entomologist, 22(2), 1997, pp. 157-166
In a four-year study (1990-1993), seven species of exotic coccinellids
[Cycloneda ancoralis (Germar): Eriopis connexa Germar, Hippodamia tre
decimpunctata Say,, H. variegata (Goeze), Oenopia conglobata (L.), Pro
pylea 14-punctata (L.), and Sycmnus frontalis F.], imported for potent
ial control oi the Russian wheal aphid. Diuraphis noxia (Kurdjumov), s
uccessfully overwintered in the Texas High Plains when caged on native
range grasses. Survival ranged from 58.6% for H. tredecimpunctata to
a low of 2.4% for S. frontalis. Differences in percentage survival ove
r years were due to climatic conditions. Higher percentage recoveries
were made in colder years with snow cover. An absence of snow cover in
conjunction with cold temperatures was more detrimental to overwinter
ing survival than warmer temperatures.