Hoverflies preying on planthopper eggs

Hoverflies (Syrphidae) are a group of flies that gets their name by their behavior of hovering in air. They look stunning beautiful and some of them mimic wasps. Eurybrachidae are family of planthoppers that are commonly seen around in gardens in India. They are considered pests for plants. While documenting insects around my home in Bangalore, I witnessed multiple times a behavior of hoverfly larvae preying on the planthopper eggs.

Eurybrachidae planthoppers lays a cluster of eggs and cover them with white material and one can see these egg clusters commonly on trees, branches, under leaves. The young ones emerges after 2-3 weeks. I regularly see planthopper egg cluster and identify them on walls and leaves. Hoverfly larvae are known to be excellent bio controllers of aphids as well as other insects. I had seen them feeding on aphids (more on it in another post).

One morning, during my morning walk I noticed a hoverfly sitting on the egg cluster of what looked like Eurybrachis species planthopper. I watched it fly around, inspect and taper the egg case. I was curious about the behavior and documented it.

I monitored the eggs for few days and searched for documented evidence of such behavior and chanced upon a reasearch article. This hover fly is thought to belong to the genus Allobaccha. The larvae of hover flies feed on eggs of the planthopper, pupate inside and emerge as adults. From then on I have noticed multiple instances of planthopper egg cases turning into pupa of hoverflies. I had witnessed whole planthopper egg case transformed into hoverfly pupa and in one case young ones of planthopper survived to hatch amongst few hoverfly pupa.

Looks like hoverflies are keeping the planthopper population under check in our garden. Indiscriminate use of pesticides are wiping out natural biocontrols like hoverflies. There is so much happening right in our backyard that we just need to observe and question.

References:

1. Allobaccha amphithoe (Walker) (Diptera, Syrphidae) a potential egg predator of white-marked gum (Eucalyptus) hopper, Platybrachys leucostigma (Walker) (Hemiptera: Eurybrachyidae)
2. Sundaram, Janarthanan & Livingstone, D. & Rabeeth, M.. (1992). Biology of the eggs of Eurybrachys tomentosa (Fabr.) (Homoptera: Fulgoridae). Hexapoda. 4. 107-112