Online Catalog     Shopping Cart
• Spiders • Projects • Lesson Plans • General Methods • Resources •
Achaearanea tepidariorum | Agelenopsis aperta | Larinioides cornutus | Physocyclus mexicanus | Hazardous Species

Achaearanea tepidariorum

Family Theridiidae (Combfooted or Cobweb Spiders)

Common House Spider

Achaearanea tepidariorum are an excellent choice for beginners of all ages as well as more advanced research. They are hardy, readily adapt to almost any kind of of container and are easy to observe in captivity and in nature.

These are pea-sized cobweb weavers, about 5-6 mm (1/4") long without legs and are very easy to recognize from their web, size and the distinctive pattern on the back of the abdomen.

The web, which looks like a tangled mess at first glance, is also called a gumfooted web. The spider hangs and swings from place to place under an open dome suspected by numerous guy lines and additional gummy lines extending down to nearby surfaces. Prey becomes entangled in the lines with drops of sticky glue near their ends and are hauled up into the web by the spider, with the assistance of numerous lines silk.

Finding Achaearanea

House spiders are commonly found in widow sills, basements, attics, cellars, sheds and barns. In nature, they are commonly found on the sides of larger trees as well as cliffs, road cuts. They tend to prefer more humid areas and can be very abundant on moist cliffs, road cuts and under bridges above or near lakes or rivers.

Containers

House spiders can grow up, mate and lay eggs in 1 ounce containers, but you will not be able to see much of their behavior or webs. It is better to keep them in liter to 10 gallon containers with clear sides for viewing the spiders. Observation cages, a few centimeters and 30-60 cm wide and high are excellent for close observation.

Environmental Conditions for Captive Spiders

Achaearanea tepidariorum appear to be tropical spiders, with relatively recent modifications for temperate climates. They can survive cold and very dry conditions as adults but the eggs and babies require warmth and relatively high humidity. They rarely make eggs sacs at low humidity and, if they do, most of the eggs will not survive.

Observing Spiders in Captivity

Achaearanea often appear to be compulsive web weavers, making webs to get themselves into secure locations off the ground as soon as they are introduced to a new container. They are also aggressive feeders and it possible to observe web building, prey capture, feeding, courtship and mating within a single one hour class period. However, it is better to give them a few days to make a full web, especially if you would like to give them more challenging prey or see more elaborate courtship behaviors.

Prey

The predatory behavior of Achaearanea is fascinating. They are very efficient predators, who can take large, powerful and very dangerous prey literally hundreds of times their own size through the effective use of silk and venom. This is roughly equivalent to a house cat grabbing a water buffalo for lunch. They may also take ants, millipedes, centipedes, harvestmen (opilionids) and many other prey with obnoxious secretions that other spiders avoid.

We give our spiders a fruit fly maggots as when they are small juveniles and housefly maggots as soon as they can take them. The will also take crickets, waxworms and mealworms but it is much more interesting to watch how they deal with a wide range of wild-caught prey.

Juvenile Achaearanea can be difficult to keep because they are incredibly small and need very small prey. We usually feed them with early instar, small fruit fly larvae and they will also take small collembolans (springtails).

Venom

Achaearanea have a very potent venom, the most insecticidal one in one comparison of a large variety of spiders. These are relatives of black widow spiders and there have been some reports of painful bites by Achaearanea but these spider have much less venom, which may be the reason why there have been no serious reactions have been reported.

Selected Links

Edwards, R.L., Edwards, E.H. (1997) Behavior and niche selection by mailbox spiders. J. Arachnol. 25:20-30. [JofA Free-Online]

Morewood, WD, Hoover, K., Sellmer, JC. Predation by Achaearanea tepidariorum (Araneae: Theridiidae) on Anoplophora glabripennis (Coleoptera: Cerambycidae). The Great Lake Entomologist 36 (1&2): p31-34. [Free PDF]

Project Ideas

Spider Bits 101

An introduction to spider biology, focusing on the development of basic skills in observations and description.

Early Development

Simply place a few eggs in mineral oil to watch the development of the embryo under a microscope.

Venoms

Is it Dangerous?

Dye dilution and locks and keys will be used to show why most spiders bites are not harmful to humans.

Boom Box Electrophysiology

A project initially described in The Laboratory Cockroach is being adapted to for venom study. 

Toxin Selectivity

Students will be shown how to remove venom glands, extract toxins and label them with a fluorescent dye. These will be used to

Courtship Behavior

How do males recognize receptive females?

How do males keep from being eaten?

How do males compete for females?

Biomechanics

How strong is the silk?

How can the spider haul in prey hundreds of times it's own size?

Ecology

Ecological consequences of differences in behavior, web structure and prey capture methods of three common house spiders will be explored.