> Out of around 40,000 spider species, _Bagheera kiplingi_ is the only spider known to have a herbivorous diet. It lives in Mexico and Costa Rica, is a species of ‘jumping spider’, and feeds mostly on protein nodules of the acacia tree. But even this spider sometimes eats ant larvae, so perhaps it is closer to the sort of vegetarian that doesn’t count prawns! > <div></div> > <cite><a href="https://www.sciencefocus.com/nature/are-there-any-vegetarian-spiders/">Luis Villazon</a></cite> --- ## Nutritional Ecology: A First Vegetarian Spider <cite>Duncan E. Jackson (via <a href="https://www.sciencedirect.com/science/article/pii/S0960982209016194">Science Direct</a>)</cite> Aggregations, or colonies, of _B. kiplingi_ established on ant–acacias have been termed ‘quasi-social’, because they differ from other social spiders in that there is no evidence of cooperative behavior between individuals. In ‘true’ social spiders, however, the primary cooperative behavior observed is usually that of group prey capture using communal webs, something which is clearly absent from the lifestyle of the vegetarian _B. kiplingi_. Characteristics that _B. kiplingi_ shares with social spiders are: - the presence of a skewed sex ratio, where females outnumber males two to one; - the observation that female spiders guard their young in breeding nests (C. Meehan, personal communication). - Although exceptional, an overlap of generations was even observed in one large breeding nest with adults, juveniles and egg clutches all being present. Clearly the social structure of _B. kiplingi_ colonies is highly reminiscent of many eusocial insects, such as ants and wasps, and this will surely provide a fruitful direction for future research by the investigators of this system. It seems that the transition from hunter to gatherer in this uniquely vegetarian spider has facilitated a suite of additional behavioral changes which might suggest an alternative route to sociality. --- ## Exploitation of the _Pseudomyrmex-Acacia_ mutualism by a predominantly vegetarian jumping spider (_Bagheera kiplingi_) <cite>Christopher J. Meehan, etc. (via <a href="https://eco.confex.com/eco/2008/techprogram/P12401.HTM">the Ecological Society of America</a>)</cite> **Background/Question/Methods** Spiders (Araneae) are morphologically diverse and employ varied foraging strategies. However, while nectar and pollen are occasional dietary supplements, virtually all of the 40,000 described species are considered obligate predators. Here we describe unique features of the ecology of _Bagheera kiplingi_ Peckham, a widespread Mesoamerican jumping spider (Salticidae) that nests on swollen-thorn acacias and consumes the plant's specialized leaf tips (Beltian bodies) and petiolar nectar as predominant components of its diet. Bagheera and its nests occurred exclusively on or adjacent to acacias occupied by _Pseudomyrmex_. Short-term translocation experiments in Costa Rica showed an elevated tendency for spiders to remain on acacias versus non-acacia shrubs. Spider occupancy was higher in wet season than dry season sampling. **Results/Conclusions** Focal spider observations, aided by use of high-definition video in Mexico, revealed that Beltian bodies accounted for > 90% of _B. kiplingi_ food items; the spiders exhibited active avoidance of ant guards while carrying out repeated foraging forays directed toward concentrations of fresh leaf tips. Spiders less frequently consumed nectar, rarely preyed on invertebrates other than ants, and even more rarely stole ant larvae being carried by _Pseudomyrmex_ workers; spiders in Mexico occasionally cannibalized other _B. kiplingi_, especially during dry-season observations. Although _Bagheera_ appeared to be territorial and foraged solitarily, populations on some individual acacias in Mexico comprised several hundred spiders. Females outnumbered males (> 2:1) among adult spiders in local populations sampled intensively; causes of this sex-ratio skew are unclear. Both summer and winter spider populations included developing eggs and individuals at all other life-stages, indicating year-round breeding and overlap among generations Cohabitation by several individuals of brood-containing nests, along with guarding by adult females of clutches and hatchlings, suggest that _Bagheera_ may be quasi-social. This study provides the first evidence of a spider exploiting or 'cheating' any obligate ant-plant mutualism. That such exploitation is being performed in a taxon never before known to feed on solid plant material is extraordinary.