Immature Stages and Biology of Apateticus cynicus (Say) (Hemiptera: Pentatomidae)

Abstract

The egg and five nymphal stages of Apateticus cynicus (Say) are described and illustrated. The nymphal stages can be separated on the basis of head-capsule width, no overlap being encountered in the specimens studied. The overall growth rate was uniform. Varying growth rates were recorded for each antennal segment. Segment one remained the shortest throughout, whereas segment four, the longest in the first stage, became shorter than segment three by the fifth stage. The second segment increased in length from 0.25 to 2.78 mm. Apateticus cynicus has one generation each year and overwinters in the egg stage in Wisconsin. Females deposit 1-3 egg batches with an average of 57.12 eggs per batch. Hatching in the laboratory took 14 days at approximately 22 °C. The average number of days spent in each of the five instars was 5.08, 5.27, 5.33, 5.0, and 9.5 respectively. Adult females lived up to 163 days and males to 180 days in the laboratory. The effectiveness of A. cynicus in the population reduction of Diprion similis (Htg.) larvae is unknown. Though a large insect and a voracious feeder throughout its immature and mature period, it has low egg production, is univoltine, and overwinters in the vulnerable egg stage, usually on the tree.