How to know when a spider wants supper

Avicularia tarantulas are some of the most beautiful tarantulas, in my opinion. They are also notoriously hard to keep as spiderlings, requiring a delicate balance of high humidity and good cross ventilation lest they succumb to mold or molting related problems. I have two that seem to be thriving. Arabella, my Avicularia cf. purpurea, is about a year old now, and the other, Tchaiovsky, Avicularia diversipes, is about 5 months. I keep them in food containers with an opening on the top and the bottom, a crapload of ventilation holes drilled in the sides and moist cotton balls instead of substrate (for now anyway). Every time I feed them I throw out the old cotton balls and put new ones in. I figure this will really decrease the opportunity for mold to develop, and it seems to work really well for these two anyway. I keep them on my desk, not on a shelf, because there is more airflow on my desk than anywhere else in the room. Plus I like watching them while I work.

 One of the things I quite like about these guys, besides their beautiful coloration and calm temperament, as well as the way the walk around lifting their limbs incredibly high in the air, is the way the let me know when they are ready for a meal. They both have a spot that they sit every time they are ready to eat. There really isn't any guess work involved, they basically look like dogs begging for a biscuit. Unfortunately these photos don't do them justice, they both are shimmery and metallic looking in just the right light, but I never seem to be able to capture that light with my camera.

Tchaikovsky

Arabella