Fig. 1: Before pupation, the caterpillar changes colour from green to brown; its horn turns blue.
When they sit quietly on trunks or leaves, their shape closely resembles that of the American B-2 Spirit stealth bomber. And they have another feature in common with the military aircraft: they are excellent and fast fliers. We are talking about the lime hawk moth (Mimas tiliae), a fairly common butterfly here.
Regularly also to be found in urban green areas
Fig. 2: Butterfly of the lime hawk moth: green variety. Photos: www.schmetterling-raupe.de
In summer, the predominantly green-coloured and inconspicuous caterpillars of the lime hawk moth feed on lime leaves. At the end of August and beginning of September, they look for a suitable hiding place in the litter layer on the ground in which to pupate. During this process, the caterpillars change colour from green to light brown. The anal horn, typical of all hawkmoth caterpillars, turns blue in colour. These striking caterpillars (Fig. 1), up to six centimetres long and as thick as a finger, are then frequently found under lime trees in urban green areas, parks and avenues.
The moths - variable and undemanding
Fig. 3: Mating; the larger moth is the female. Photo: R. Johannsmann
The butterflies hatch in May of the following year. The moths have a wingspan of 60 to 80 millimetres. Their basic colouring is very variable, so that green, brown, pink or silvery coloured moths are to be found. The moths of the Mimas genus are easily recognisable by the wavy outer edges of the forewings, as is the case with the lime hawk moth (Fig. 2). They are excellent flyers. As the proboscis of the moths is atrophied, they, like the eyed hawk moth (Smerinthus ocellata) and the poplar hawk moth (Laothoe populi), do not feed. So you will never spot them on flowers.
The females lay their eggs individually or in pairs on the underside of lime leaves, generally above a height of around four metres. The caterpillars that hatch from them feed quite inconspicuously on the foliage from June to August. In stormy weather, caterpillars that have fallen can occasionally be found on the ground. In addition to the lime tree, the birch is also used as a food plant.
