Bloodbug Bloodbugs are a species of mutated , ectoparasitic found in the Commonwealth in 2287 . Background . The bloodbug appears to be a monstrously enlarged mutated form of mosquito . Likely a byproduct of mutation caused by nuclear fallout ; they have grown in size over the time period since the Great War in a manner similar to radroaches and bloatflies . Characteristics . Biology . Bloodbugs appear to be roughly two feet in length from the head to the tip of the abdomen . Bloodbugs possess muddy brown coloration which allows them to camouflage effectively into the environment of the Commonwealth . Like their pre - War ancestors , bloodbugs possess six long double - jointed limbs , one pair of finely - veined wings and a long , pointed proboscis that extends from between two compound eyes . The proboscis is the bloodbug ' s primary means of assault , sinking it into prey almost like a syringe and inflicting minor - to - intermediate radiation poisoning on the victim . The proboscis can be collected by the Sole Survivor upon the bloodbug ' s death . Gameplay attributes . Bloodbugs latch onto their prey in an attempt to drink their blood . The insect then becomes engorged with the victim ' s blood , and can spit the contaminated blood back at its target for a large amount of radiation damage , which suggests that radiation is transmitted from the mutant to the victim . While these mutated mosquitoes can punch their proboscis through any kind of regular armor , it ' s not powerful enough to penetrate power armor . Should they find themselves faced with such heavily armored prey , their range of available attacks becomes limited to largely ineffectual stings and their acid spit , should the target be out of melee range . Bloodbugs are often encountered feeding on deceased brahmin . Coming across the exsanguinated , grey - skinned husk of a dead brahmin whose body is covered in oversized stings is a significant indicator of knowing there are bloodbugs nearby . Bloodbugs near certain parts of the coast are occasionally seen feeding on the corpses of sea creature s . Bloodbugs , like bloatflies and radscorpions , have a propensity for swarming tactics . Once they are alerted to their victim ' s presence , they will spread out , surround their prey and attack from multiple directions . This , coupled with their erratic evasive movement while under fire , their good camouflage and their slender silhouette , makes it difficult to keep track of and kill them all before at least some of them get into melee range . However , should the majority of the swarm be destroyed before it reaches its prey , the survivors will often retreat . Usually they will regroup and attack again , but sometimes they will flee for good without returning . Another habit bloodbugs share with bloatflies and especially radroaches is their clinging to trees and structures , as well as walls or the ceiling while indoors and unaware of an enemy ' s presence . This can result in a nasty surprise when the player character enters a seemingly empty room or subway station and suddenly finds themselves in the middle of an entire bloodbug swarm . Companions will usually notice the bugs and remark upon something not being right or enemies being nearby , although they won ' t open fire until the creatures make the first move . Their comments can still provide a valuable warning though . If the Sole Survivor damages the bloodbug ' s blood sac , it will lose its spit ability , but the bloodbug can still suck the victim ' s blood . If done multiple times , the bloodbug ' s sac will be restored and it will regain its spit attack . Some bloodbugs near dead brahmin can be found with their blood sac already full of the brahmin ' s blood . The bloodbug ' s enlarged blood sac can be targeted more accurately due to its size . Variants . Bloodbug hatchling . A younger variant of the adult bloodbug , their exoskeleton has not had time to harden to the extent of more mature bloodbugs , thus they are paler and weaker . Common in the area around Sanctuary Hills , the road between Concord and the Red Rocket truck stop early in - game , although are still relatively common in other parts of the Commonwealth . They are the weakest form of bloodbugs . Bloodbug . The most common variant of the bloodbug ; the typical mature form . They can be found in numerous locations throughout the Commonwealth . Red widow bloodbug . A rare variant of the bloodbug that is found in the Glowing Sea and which may spawn at random in some other areas in the Commonwealth . They are of similar size to normal bloodbugs , but their bodies are tinted red . They are markedly more aggressive and much deadlier than other variants . Infected bloodbug . They possess more health than a normal adult bloodbug and deal more damage per hit . Some specimens also have green exoskeletons . One can be found in the basement of the Greater Mass blood clinic . It is initially non - aggressive , and even killing the surrounding bloodbugs does not incite it to attack . This variation is very common in the Glowing Sea , where it is hostile like all other bloodbugs . Glowing bloodbug . A rare variant inundated with radiation to such an extent that it glows . It is stronger and more resilient than many of the other bloodbug variants . Vampiric bloodbug . The vampiric bloodbug can be found in various locations throughout the Commonwealth . It is the strongest variant of these creatures , and is much more deadly than its counterparts . Appearances . Bloodbugs appear only in " Fallout 4 " . Behind the scenes . The bloodbug model was created by Jonah Lobe .