Nature Gardens at NHM: LA's Urban Nature

Showing posts with label : black widow

September 22, 2012

Q: What are Those Miniature Spiky Puffballs? A: Brown Widow Egg Sacs

Earlier this week, staff found some small circular egg cases on a gate in the North Campus. Upon closer inspection we realized they were brown widow, Latrodectus geometricus, egg sacs. But how did we know this?

Two egg sacs, each containing about 100 eggs,
notice the geometric design.

Differences between brown widows and western black widows:

Brown Widows
Egg sacs are pale yellow and spiky (BINGO)
Egg sacs contain upto 150 spiderlings (best word ever)
Can lay 20 sacs over their lifespan
Adult females are USUALLY tan with an orange hourglass design on the underside of the abdomen
Lower incidence of medically significant spider bites

Western Black Widows...