Aboard a spider--a complex developmental strategy fossilized in amber.

Area of Science:

• Paleontology
• Entomology
• Evolutionary Biology

Background:

• Mantid flies (Mantispidae) are lacewings (Neuroptera) with adults resembling mantids.
• Mantispidae larvae typically prey on spider eggs, employing strategies like "spider-boarding."
• The larval stages include a mobile first instar and immobile later instars.

Purpose of the Study:

• To report the first fossil record of a mantispid larva.
• To document the earliest fossil evidence of mantispid complex larval behavior and development.
• To identify the first Mantispidae fossil from Baltic amber.

Main Methods:

• Discovery and analysis of a fossilized mantispid larva in Middle Eocene Baltic amber.
• Observation of the larva's attachment to a clubionoid spider.
• Comparison of the fossil's position with known extant mantispid larval behavior.

Main Results:

• The first fossil mantispid larva was identified in Middle Eocene Baltic amber.
• This represents the first record of Mantispidae in this fossil deposit.
• The larva was found attached to a spider, indicating the fossilization of "spider-boarding" behavior.

Conclusions:

• The fossil provides the first direct evidence of mantispid larval parasitism on spiders in the fossil record.
• This finding extends the known history of this specialized predatory behavior.
• The discovery highlights the paleoecological interactions between ancient insects and arachnids.