The Marine Gardens at Crosby, Merseyside (SJ315980) comprise four walled ornamental public gardens, running from south to north and situated along the south-eastern perimeter of Crosby Marine Park.
The gardens cover 4.86 hectares and total c.900m in length and c.50m wide.
The site contains extensive lawns, bordered by flower beds, mainly planted with shrubs and hardy flowering plants.
Several of the south and south-west facing perimeter walls are overgrown with Ivy, Hedera sp. (Fig.1), which provides a vital pollen and nectar source for insects in the Autumn.
During 2018-2022, I made regular visits to the site, recording the insects present there. The recording season started in March and lasted until November, with further occasional visits in December, weather permitting. The main focus were Hoverflies (Syrphidae), along with other Diptera and also Bees and Wasps (Hymenoptera).
During the recording period, 61 species of Syrphids were noted at the site, which represents c.30% of the total number of hoverfly species that have been recorded on the Sefton Coast.
The gardens are a key site for Eristalinus aeneus (Fig. 2). This is primarily a coastal species in Britain, with a very scattered distribution. It is unusual among British hoverflies in that it overwinters as an adult. The majority of records for VC59 and Sefton Coast have been made at this site in March and October. The Autumn individuals can often be found on the flowering Ivy.
Two of the largest and most eye-catching hoverflies in Britain are the Hornet mimics. Both Volucella zonaria (Fig. 3) and Volucella inanis have been recorded on numerous occasions in the Marine Gardens during the study period. Both species are relatively recent additions to the fauna of Lancashire, being first recorded in 2012 and 2017 respectively. The flight period begins in July for both insects and can extend to October for zonaria, with inanis on the wing until August. Both species can be found on Bramble and Buddleja flowers, with zonaria being another Ivy flower user in Autumn.
The hoverfly population in Britain is enhanced by several migrant species from Europe during the year, mainly arriving during warm weather in late Summer. Several of these migrants have been recorded in the gardens, including Scaeva pyrastri, Eupeodes latifasciatus and Episyrphus balteatus.
Two rarer migrant Syrphids have also been recorded during the study period; Eupeodes lapponicus (Fig.4) and Xanthandrus comtus. E. lapponicus has just four recent records in VC59, including the Crosby sighting in July 2019. X. comtus has a scattering of Vice-County records, with nine being recorded in the last few years on the Sefton Coast, including females at the Marine Gardens in 2020 and 2022.
Several other notable Diptera have been recorded in the gardens. One species, a large Tachinid, Linnaemya picta (Fig.5), is a southern species spreading north, first recorded locally at Formby in 2020, and photographed at the Marine Gardens on 19th September of that same year.
One of the most interesting of the flies recorded during the study period was the Locust Blowfly, Stomorhina lunata (Fig.6). This is mainly a North African species that occasionally wanders north into Europe and is a vagrant to Britain. The first record in the gardens, a female, was photographed on 19th September 2020.
Then in October 2022, an unprecedented influx occurred, with six individuals (five males and a female) recorded between the 2nd and the 6th of the month. This species, as the name suggests, is a parasite of the younger stages of Locusts, but is not thought to target Orthoptera in Britain.
The stand-out Bee species recorded in the gardens during the study period was the Ivy Bee, Colletes hederae (Fig.7). This species first arrived in Britain from Southern Europe in 2001 and has steadily moved north since. The first Merseyside records were just to the north along the coast in 2018 and a few days later the species was photographed in the Marine Gardens. The site hosts hundreds of Ivy Bees in September and October, feeding amongst hoverflies and other insects on the south facing Ivy clumps.
Mainly a southern species that is gradually moving north, the Yellow-legged Mining Bee, Andrena flavipes (Fig.8) is a rare species in North Merseyside / Lancashire. Two have been recorded in the Marine Gardens, in March 2019 and April 2021.
Another recent arrival to the Sefton coast is the Ornate -tailed Digger Wasp, Cerceris rybyensis (Fig.9). This is another southern species that is gradually moving northwards in Britain. It was first recorded in Merseyside in 2020 and then subsequently photographed in the Marine Gardens in 2021. This is a large predatory solitary wasp, which preys on various small bees.