Dispersal, survival, and population abundance of gypsy moth, Lymantria dispar (Lepidoptera: Lymantriidae), larvae determined by releases and mark-recapture studies

The author studied dispersal of gypsy moths, Lymantria dispar (L.), released as eggs into a naturally low gypsy moth population, and retention of small larvae on isolated oak terminals in the same area. Most larvae recovered after eggs hatched were close to the release point and dispersed randomly shortly thereafter. Larvae were lost from branch terminals, but usually at least 80% were retained from one day to the next. The author also carried out a mark-recapture study of large larvae in this same area, as well as in another area with a moderately high infestation. Caterpillars were marked by selectively removing prolegs. Dispersal patterns of larvae at both sites were similar and population densities were about 10,000 and 400,000 larvae per ha at the low- and high-population sites, respectively. Survival rates were highest at the high-population site. Estimated population values were closely correlated with the number of large caterpillars found under burlap bands, suggesting that the latter may usefully indicate absolute population levels.