You didn't mention what type of flowering plant you have in your apartment?  So, here's my recent houseplant aphid experience; I hope this info is helpful--at least it's another approach to consider.

I recently purchased a Meyer Lemon tree and immediately spotted APHIDS! I want lemons, not insects!! The tree, which had been in a nursery greenhouse, was brought into my house, and, most likely, with the change in environment, the aphids appeared. Once I noticed, the aphids, happily feasting on several leaves and flower buds, I took the tree into the shower and sprayed off the pests--(Note:  you must spray the top and bottoms of leaves). After trying this for a week, I decided to take more action. I visited the nursery where I purchased the tree, explained the problem, and was told to "spray the tree with water" to knock off the aphids. Since I had been doing this for a week, I talked it over with the nursery manager who agreed I should try an insecticide safe for use on a fruit tree. I purchased "Green Light NEEM II." This insecticide is registered for use on fruits, nuts, vegetables, herbs, spices, roses, houseplants, flowers, and shrubs. The label recommends spraying every 7-14 days. I plan to take a more conservative approach. I sprayed the tree outside, carefully spraying the entire plant--top and bottom of all leaves, buds, and flowers, and allowed it to dry before bringing it back inside.  Since spraying 2 1/2 weeks ago and I have seen no pests and will avoid spraying again unless absolutely necessary. I also repotted the tree with new potting soil and a slightly larger pot.

As a way to prevent further problems, I am practicing good plant hygiene by picking up fallen leaves and flowers, misting the tree to encourage good humidity, and watering the appropriate amount each week.  For now, I have the tree isolated from all other houseplants to avoid a mass infestation.  

Would I bring in beneficial nematodes or other predators for houseplants?  No.  If you decide to spray, make sure you select a product that is recommended for the pest you are trying to control (aphids) and make sure the label says the product is registered for use on your plant.  Well, I hope this helps!