His Imperial Majesty: A Natural History of the Purple Emperor by Matthew Oates

Author:Matthew Oates [Oates, Matthew]
Language: eng
Format: epub
Tags: nature, animals, Butterflies & Moths, Insects & Spiders, Ecology, Wildlife, science, Life Sciences, Zoology, Entomology, General
ISBN: 9781472950130
Google: hXTmDwAAQBAJ
Publisher: Bloomsbury Publishing
Published: 2020-06-11T23:53:39.745263+00:00

The entire world seems to be set against the survival of baby caterpillars, known by entomologists as first-instar or L1 larvae. Survival rates are low, with larvae readily succumbing to a variety of predatory invertebrates – various ants, beetles, bugs, hunting spiders, wasps, weevils and earwigs. One Victorian vicar confessed in one of the entomological journals to suffering recurrent nightmares about ‘monstrous earwigs’ consuming his precious Purple Emperor larvae, kept in a muslin bag (known as a ‘sleeve’) on a sallow branch in his garden.

Denys Watkins-Pitchford (BB) believed that the Common Flower Bug is a major predator of infant Purple Emperor larvae. Its mouthparts are strong enough to pierce human flesh. He had nightmares about it. However, it is more likely that his problem species was the highly similar Anthocoris nemoralis (often called the Common Tree Flower Bug) which occurs commonly on trees.

Expert butterfly breeders Martin White and Colin Wiskin hold that flower bugs are major predators in captivity, and I have also lost captive Purple Emperor larvae to these small heteropteran bugs – by failing to ensure newly sleeved foliage was free of them. In the wild, I have recorded L1 larvae being killed or taken by flower bugs, common social wasps and, in one instance, the Brown Tree Ant, a very local arboreal species. Dennis Dell once watched an L1 larva being carried off by ‘a brown ant’. In addition, it is likely that arboreal species of shieldbugs, notably the Red-legged Shieldbug, as well as the Tree Damsel Bug, the larvae of various arboreal lacewings (Neuroptera) and the Harlequin Ladybird, are major predators of young Purple Emperor larvae – the problem is catching them in the act. These should all be presumed guilty until proven innocent.

Wasps may well be major predators. However, the two similar-looking species of social wasp that constitute what we call the ‘common wasp’ (the true Common Wasp and the German Wasp) were relatively scarce during the bulk of the period 2009–19, in which most of my studies took place. The scanty evidence that is available suggests that their populations collapsed during the excessively wet summer of 2012 and only started to recover properly during the hot summer of 2018. The problem here is that wasp populations, unlike those of butterflies, are not yet being closely monitored in the UK.

Infant Purple Emperor larvae, measuring 3 millimetres long when newly hatched, are highly prone to being washed off the leaves by heavy rain during their first few hours of life. Even a short, sharp shower can cause losses of newly hatched larvae, while a heavy thunderstorm can be devastating. After a few hours, as Frohawk discovered, they spin some silk strands, to form a loose pad to which their rear claspers can properly adhere. Once they are a few days old, and have spun a proper pad, they are not easily washed away.

On a leaf, L1 larvae usually rest, when not feeding, on the midrib extremity, always facing inwards towards the stalk, on leaf tips that are often curled and downward-pointing, and which therefore act as funnels for water run-off.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.