Cornfield Bolas Spider

The female spiders have a large spherical abdomen with a milky white base often covered in darker brown patterns and a smaller brown carapace. There is a clear distinction between the two sexes as extreme sexual dimorphism results in much larger females. Although both sexes hatch with their cephalothorax range being around 0.5 mm, the female develops into a significantly larger specimen than her male counterpart. The size difference coheres with the divergence of their respective hunting behaviors. While female bolas spiders hang from a horizontal thread waiting to swing her bolas or sticky orb towards her nearby prey (typically moths), the males do not use a bolas but implement hunting tactics reminiscent of early-instar spiders.

Mastophora are widely distributed throughout the world in temperate climates except for Euro Asia and South Africa. The M. hutchinsoni primarily reside in the northeastern regions of North America near areas of a more temperate climate. The range of locations in North America are from Minnesota to New Hampshire.

As a result of a highly specialized hunting technique that mimics the disparate chemical compositions of its prey, the hunting range for the M. hutchinsoni is limited to a couple families of male moths. The females typically hunt either Noctuidae moths consisting of the bristly cut-worm, bronzed cutworm, and smoky tetanolita or the bluegrass worm of the Pyralidae family during prime activity hours in the evening, which results in nocturnal hunting patterns. In particular, the Lacinipolia renigera (bristly cut-worm) constitutes two-thirds of total prey biomass and, together with the Tetanolita mynesalis (smoky tetanolita), makes up to ninety percent of the overall diet of M. hutchinsoni. Adult females will often capture more than one moth per night.