Bedbugs are parasitic insects that feed on the blood of humans. Fortunately, they are not known to transmit diseases. Adult bedbugs are brown, flat, oval-shaped and the size of an apple seed. After feeding on blood, bedbugs swell and turn reddish in color. Bedbugs hide when they are not feeding. Some humans show no reaction to being bitten by bedbugs other than two small dots where the bedbugs have punctured their skin. Those who are more sensitive may develop reddish bumps or lesions on their skin within 12 hours of being bitten. The bumps/lesions tend to swell and become itchy within 24 to 48 hours. If scratched, they can become infected. In rare instances, people have experienced systemic allergic reactions to bedbug bites. Allergic reactions can include asthma, generalized hives, and anaphylactic shock. A study conducted by scientists in Montreal also found a link between bed bug infestation and symptoms of sleep disturbances and anxiety.