Juniper Shieldbug a species on Lawson Cypress

 

Perhaps my most long awaited new shieldbug species for Yorkshire has been the Juniper Shieldbug Cyphostethus tristriatus, ever since the beginning of its range expansion from southern England 10-15 years or so ago. Historically a species limited to Juniper Juniperus woodlands in southern England, this species has rapidly expanded largely through the planting of Junipers and Cypress's in gardens. This species appears to be particularly dependent on Lawson Cypress Chamaecyparis lawsoniana, which frequently produces cones, thought to be important for feeding, nymphal development and egg laying. It is however recorded from Leyland Cypress Cupressus x leylandii and Nootka Cypress Chamaecyparis nootkatensis are also known foodplants. Having checked the large (non-cone producing) Leylandii hedge around my garden almost daily for this species it doesn't seem too keen on it, which favours the cone argument. Certainly a useful prerequisite to finding these locally is to find areas with cone producing Lawson Cypress. 

This small colony was found by a friend in a private farmyard just off the A64 near Staxton and included a nice breeding colony including numerous nymphs, suggesting establishment there of at least this summer if not earlier. Having never seen this shieldbug I certainly wasn't disappointed and am looking forward to revisiting during the spring to study its mating and egg laying ecology. Due to the cool weather there was no sign of them, so we laid down a sheet and gave the bush a few shakes and quickly recorded a nice mixture of nymphs and adults, which had dropped onto the sheet, certainly a worthwhile technique for recording this species. 

As with other locally occurring Acanthosomatid shieldbugs the Juniper Shieldbug shares a similar phenology overwintering as an adult, laying eggs in the spring. Then these develop as a summer generation which then lays eggs in late summer/autumn for these eggs to hatch develop into adults, overwinter and complete the cycle. Unlike similar species like Hawthorn Shieldbug Acanthosoma haemorrhoidale and Birch Shieldbug Elasmostethus interstinctus which feed on deciduous trees and therefore overwinter at ground level amongst places like rotten tree stumps and beneath logs, Juniper Shieldbug presumably retreats into the dense recesses of the needles of the Juniper or Cypress it frequents. I have failed to find any information on this, so certainly warrants an extra look at with this colony.